Versioning Java GeneratedMessage.

Change-Id: Ib2bb5042deaabdf452d5be2ad1ce40d739ad8d1b

4 files changed, 2718 insertions, 347 deletions

diff --git a/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java b/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java
new file mode 100644
index 00000000..5dfe7ff7
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java
@@ -0,0 +1,2716 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.EnumDescriptor;
+import com.google.protobuf.Descriptors.EnumValueDescriptor;
+import com.google.protobuf.Descriptors.FieldDescriptor;
+import com.google.protobuf.Descriptors.FileDescriptor;
+import com.google.protobuf.Descriptors.OneofDescriptor;
+import com.google.protobuf.GeneratedMessage.GeneratedExtension;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.ObjectStreamException;
+import java.io.Serializable;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * All generated protocol message classes extend this class.  This class
+ * implements most of the Message and Builder interfaces using Java reflection.
+ * Users can ignore this class and pretend that generated messages implement
+ * the Message interface directly.
+ *
+ * @author kenton@google.com Kenton Varda
+ */
+public abstract class GeneratedMessageV3 extends AbstractMessage
+    implements Serializable {
+  private static final long serialVersionUID = 1L;
+
+  /**
+   * For testing. Allows a test to disable the optimization that avoids using
+   * field builders for nested messages until they are requested. By disabling
+   * this optimization, existing tests can be reused to test the field builders.
+   */
+  protected static boolean alwaysUseFieldBuilders = false;
+
+  /** For use by generated code only.  */
+  protected UnknownFieldSet unknownFields;
+
+  protected GeneratedMessageV3() {
+    unknownFields = UnknownFieldSet.getDefaultInstance();
+  }
+
+  protected GeneratedMessageV3(Builder<?> builder) {
+    unknownFields = builder.getUnknownFields();
+  }
+
+  @Override
+  public Parser<? extends GeneratedMessageV3> getParserForType() {
+    throw new UnsupportedOperationException(
+        "This is supposed to be overridden by subclasses.");
+  }
+
+ /**
+  * For testing. Allows a test to disable the optimization that avoids using
+  * field builders for nested messages until they are requested. By disabling
+  * this optimization, existing tests can be reused to test the field builders.
+  * See {@link RepeatedFieldBuilder} and {@link SingleFieldBuilder}.
+  */
+  static void enableAlwaysUseFieldBuildersForTesting() {
+    alwaysUseFieldBuilders = true;
+  }
+
+  /**
+   * Get the FieldAccessorTable for this type.  We can't have the message
+   * class pass this in to the constructor because of bootstrapping trouble
+   * with DescriptorProtos.
+   */
+  protected abstract FieldAccessorTable internalGetFieldAccessorTable();
+
+  @Override
+  public Descriptor getDescriptorForType() {
+    return internalGetFieldAccessorTable().descriptor;
+  }
+
+  /**
+   * Internal helper to return a modifiable map containing all the fields.
+   * The returned Map is modifialbe so that the caller can add additional
+   * extension fields to implement {@link #getAllFields()}.
+   *
+   * @param getBytesForString whether to generate ByteString for string fields
+   */
+  private Map<FieldDescriptor, Object> getAllFieldsMutable(
+      boolean getBytesForString) {
+    final TreeMap<FieldDescriptor, Object> result =
+      new TreeMap<FieldDescriptor, Object>();
+    final Descriptor descriptor = internalGetFieldAccessorTable().descriptor;
+    final List<FieldDescriptor> fields = descriptor.getFields();
+
+    for (int i = 0; i < fields.size(); i++) {
+      FieldDescriptor field = fields.get(i);
+      final OneofDescriptor oneofDescriptor = field.getContainingOneof();
+
+      /*
+       * If the field is part of a Oneof, then at maximum one field in the Oneof is set
+       * and it is not repeated. There is no need to iterate through the others.
+       */
+      if (oneofDescriptor != null) {
+        // Skip other fields in the Oneof we know are not set
+        i += oneofDescriptor.getFieldCount() - 1;
+        if (!hasOneof(oneofDescriptor)) {
+          // If no field is set in the Oneof, skip all the fields in the Oneof
+          continue;
+        }
+        // Get the pointer to the only field which is set in the Oneof
+        field = getOneofFieldDescriptor(oneofDescriptor);
+      } else {
+        // If we are not in a Oneof, we need to check if the field is set and if it is repeated
+        if (field.isRepeated()) {
+          final List<?> value = (List<?>) getField(field);
+          if (!value.isEmpty()) {
+            result.put(field, value);
+          }
+          continue;
+        }
+        if (!hasField(field)) {
+          continue;
+        }
+      }
+      // Add the field to the map
+      if (getBytesForString && field.getJavaType() == FieldDescriptor.JavaType.STRING) {
+        result.put(field, getFieldRaw(field));
+      } else {
+        result.put(field, getField(field));
+      }
+    }
+    return result;
+  }
+
+  @Override
+  public boolean isInitialized() {
+    for (final FieldDescriptor field : getDescriptorForType().getFields()) {
+      // Check that all required fields are present.
+      if (field.isRequired()) {
+        if (!hasField(field)) {
+          return false;
+        }
+      }
+      // Check that embedded messages are initialized.
+      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+        if (field.isRepeated()) {
+          @SuppressWarnings("unchecked") final
+          List<Message> messageList = (List<Message>) getField(field);
+          for (final Message element : messageList) {
+            if (!element.isInitialized()) {
+              return false;
+            }
+          }
+        } else {
+          if (hasField(field) && !((Message) getField(field)).isInitialized()) {
+            return false;
+          }
+        }
+      }
+    }
+
+    return true;
+  }
+
+  @Override
+  public Map<FieldDescriptor, Object> getAllFields() {
+    return Collections.unmodifiableMap(
+        getAllFieldsMutable(/* getBytesForString = */ false));
+  }
+
+  /**
+   * Returns a collection of all the fields in this message which are set
+   * and their corresponding values.  A singular ("required" or "optional")
+   * field is set iff hasField() returns true for that field.  A "repeated"
+   * field is set iff getRepeatedFieldCount() is greater than zero.  The
+   * values are exactly what would be returned by calling
+   * {@link #getFieldRaw(Descriptors.FieldDescriptor)} for each field.  The map
+   * is guaranteed to be a sorted map, so iterating over it will return fields
+   * in order by field number.
+   */
+  Map<FieldDescriptor, Object> getAllFieldsRaw() {
+    return Collections.unmodifiableMap(
+        getAllFieldsMutable(/* getBytesForString = */ true));
+  }
+
+  @Override
+  public boolean hasOneof(final OneofDescriptor oneof) {
+    return internalGetFieldAccessorTable().getOneof(oneof).has(this);
+  }
+
+  @Override
+  public FieldDescriptor getOneofFieldDescriptor(final OneofDescriptor oneof) {
+    return internalGetFieldAccessorTable().getOneof(oneof).get(this);
+  }
+
+  @Override
+  public boolean hasField(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field).has(this);
+  }
+
+  @Override
+  public Object getField(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field).get(this);
+  }
+
+  /**
+   * Obtains the value of the given field, or the default value if it is
+   * not set.  For primitive fields, the boxed primitive value is returned.
+   * For enum fields, the EnumValueDescriptor for the value is returned. For
+   * embedded message fields, the sub-message is returned.  For repeated
+   * fields, a java.util.List is returned. For present string fields, a
+   * ByteString is returned representing the bytes that the field contains.
+   */
+  Object getFieldRaw(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field).getRaw(this);
+  }
+
+  @Override
+  public int getRepeatedFieldCount(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field)
+      .getRepeatedCount(this);
+  }
+
+  @Override
+  public Object getRepeatedField(final FieldDescriptor field, final int index) {
+    return internalGetFieldAccessorTable().getField(field)
+      .getRepeated(this, index);
+  }
+
+  @Override
+  public UnknownFieldSet getUnknownFields() {
+    throw new UnsupportedOperationException(
+        "This is supposed to be overridden by subclasses.");
+  }
+
+  /**
+   * Called by subclasses to parse an unknown field.
+   * @return {@code true} unless the tag is an end-group tag.
+   */
+  protected boolean parseUnknownField(
+      CodedInputStream input,
+      UnknownFieldSet.Builder unknownFields,
+      ExtensionRegistryLite extensionRegistry,
+      int tag) throws IOException {
+    return unknownFields.mergeFieldFrom(tag, input);
+  }
+
+  protected static <M extends Message> M parseWithIOException(Parser<M> parser, InputStream input)
+      throws IOException {
+    try {
+      return parser.parseFrom(input);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.unwrapIOException();
+    }
+  }
+
+  protected static <M extends Message> M parseWithIOException(Parser<M> parser, InputStream input,
+      ExtensionRegistryLite extensions) throws IOException {
+    try {
+      return parser.parseFrom(input, extensions);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.unwrapIOException();
+    }
+  }
+
+  protected static <M extends Message> M parseWithIOException(Parser<M> parser,
+      CodedInputStream input) throws IOException {
+    try {
+      return parser.parseFrom(input);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.unwrapIOException();
+    }
+  }
+
+  protected static <M extends Message> M parseWithIOException(Parser<M> parser,
+      CodedInputStream input, ExtensionRegistryLite extensions) throws IOException {
+    try {
+      return parser.parseFrom(input, extensions);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.unwrapIOException();
+    }
+  }
+
+  protected static <M extends Message> M parseDelimitedWithIOException(Parser<M> parser,
+      InputStream input) throws IOException {
+    try {
+      return parser.parseDelimitedFrom(input);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.unwrapIOException();
+    }
+  }
+
+  protected static <M extends Message> M parseDelimitedWithIOException(Parser<M> parser,
+      InputStream input, ExtensionRegistryLite extensions) throws IOException {
+    try {
+      return parser.parseDelimitedFrom(input, extensions);
+    } catch (InvalidProtocolBufferException e) {
+      throw e.unwrapIOException();
+    }
+  }
+
+  @Override
+  public void writeTo(final CodedOutputStream output) throws IOException {
+    MessageReflection.writeMessageTo(this, getAllFieldsRaw(), output, false);
+  }
+
+  @Override
+  public int getSerializedSize() {
+    int size = memoizedSize;
+    if (size != -1) {
+      return size;
+    }
+
+    memoizedSize = MessageReflection.getSerializedSize(
+        this, getAllFieldsRaw());
+    return memoizedSize;
+  }
+
+
+
+  /**
+   * Used by parsing constructors in generated classes.
+   */
+  protected void makeExtensionsImmutable() {
+    // Noop for messages without extensions.
+  }
+
+  /**
+   * TODO(xiaofeng): remove this after b/29368482 is fixed. We need to move this
+   * interface to AbstractMessage in order to versioning GeneratedMessageV3 but
+   * this move breaks binary compatibility for AppEngine. After AppEngine is
+   * fixed we can exlude this from google3.
+   */
+  protected interface BuilderParent extends AbstractMessage.BuilderParent {}
+
+  /**
+   * TODO(xiaofeng): remove this together with GeneratedMessageV3.BuilderParent.
+   */
+  protected abstract Message.Builder newBuilderForType(BuilderParent parent);
+
+  @Override
+  protected Message.Builder newBuilderForType(final AbstractMessage.BuilderParent parent) {
+    return newBuilderForType(new BuilderParent() {
+      @Override
+      public void markDirty() {
+        parent.markDirty();
+      }
+    });
+  }
+
+
+  @SuppressWarnings("unchecked")
+  public abstract static class Builder <BuilderType extends Builder<BuilderType>>
+      extends AbstractMessage.Builder<BuilderType> {
+
+    private BuilderParent builderParent;
+
+    private BuilderParentImpl meAsParent;
+
+    // Indicates that we've built a message and so we are now obligated
+    // to dispatch dirty invalidations. See GeneratedMessageV3.BuilderListener.
+    private boolean isClean;
+
+    private UnknownFieldSet unknownFields =
+        UnknownFieldSet.getDefaultInstance();
+
+    protected Builder() {
+      this(null);
+    }
+
+    protected Builder(BuilderParent builderParent) {
+      this.builderParent = builderParent;
+    }
+
+    @Override
+    void dispose() {
+      builderParent = null;
+    }
+
+    /**
+     * Called by the subclass when a message is built.
+     */
+    protected void onBuilt() {
+      if (builderParent != null) {
+        markClean();
+      }
+    }
+
+    /**
+     * Called by the subclass or a builder to notify us that a message was
+     * built and may be cached and therefore invalidations are needed.
+     */
+    @Override
+    protected void markClean() {
+      this.isClean = true;
+    }
+
+    /**
+     * Gets whether invalidations are needed
+     *
+     * @return whether invalidations are needed
+     */
+    protected boolean isClean() {
+      return isClean;
+    }
+
+    @Override
+    public BuilderType clone() {
+      BuilderType builder =
+          (BuilderType) getDefaultInstanceForType().newBuilderForType();
+      builder.mergeFrom(buildPartial());
+      return builder;
+    }
+
+    /**
+     * Called by the initialization and clear code paths to allow subclasses to
+     * reset any of their builtin fields back to the initial values.
+     */
+    @Override
+    public BuilderType clear() {
+      unknownFields = UnknownFieldSet.getDefaultInstance();
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /**
+     * Get the FieldAccessorTable for this type.  We can't have the message
+     * class pass this in to the constructor because of bootstrapping trouble
+     * with DescriptorProtos.
+     */
+    protected abstract FieldAccessorTable internalGetFieldAccessorTable();
+
+    @Override
+    public Descriptor getDescriptorForType() {
+      return internalGetFieldAccessorTable().descriptor;
+    }
+
+    @Override
+    public Map<FieldDescriptor, Object> getAllFields() {
+      return Collections.unmodifiableMap(getAllFieldsMutable());
+    }
+
+    /** Internal helper which returns a mutable map. */
+    private Map<FieldDescriptor, Object> getAllFieldsMutable() {
+      final TreeMap<FieldDescriptor, Object> result =
+        new TreeMap<FieldDescriptor, Object>();
+      final Descriptor descriptor = internalGetFieldAccessorTable().descriptor;
+      final List<FieldDescriptor> fields = descriptor.getFields();
+
+      for (int i = 0; i < fields.size(); i++) {
+        FieldDescriptor field = fields.get(i);
+        final OneofDescriptor oneofDescriptor = field.getContainingOneof();
+
+        /*
+         * If the field is part of a Oneof, then at maximum one field in the Oneof is set
+         * and it is not repeated. There is no need to iterate through the others.
+         */
+        if (oneofDescriptor != null) {
+          // Skip other fields in the Oneof we know are not set
+          i += oneofDescriptor.getFieldCount() - 1;
+          if (!hasOneof(oneofDescriptor)) {
+            // If no field is set in the Oneof, skip all the fields in the Oneof
+            continue;
+          }
+          // Get the pointer to the only field which is set in the Oneof
+          field = getOneofFieldDescriptor(oneofDescriptor);
+        } else {
+          // If we are not in a Oneof, we need to check if the field is set and if it is repeated
+          if (field.isRepeated()) {
+            final List<?> value = (List<?>) getField(field);
+            if (!value.isEmpty()) {
+              result.put(field, value);
+            }
+            continue;
+          }
+          if (!hasField(field)) {
+            continue;
+          }
+        }
+        // Add the field to the map
+        result.put(field, getField(field));
+      }
+      return result;
+    }
+
+    @Override
+    public Message.Builder newBuilderForField(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field).newBuilder();
+    }
+
+    @Override
+    public Message.Builder getFieldBuilder(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field).getBuilder(this);
+    }
+
+    @Override
+    public Message.Builder getRepeatedFieldBuilder(final FieldDescriptor field, int index) {
+      return internalGetFieldAccessorTable().getField(field).getRepeatedBuilder(
+          this, index);
+    }
+
+    @Override
+    public boolean hasOneof(final OneofDescriptor oneof) {
+      return internalGetFieldAccessorTable().getOneof(oneof).has(this);
+    }
+
+    @Override
+    public FieldDescriptor getOneofFieldDescriptor(final OneofDescriptor oneof) {
+      return internalGetFieldAccessorTable().getOneof(oneof).get(this);
+    }
+
+    @Override
+    public boolean hasField(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field).has(this);
+    }
+
+    @Override
+    public Object getField(final FieldDescriptor field) {
+      Object object = internalGetFieldAccessorTable().getField(field).get(this);
+      if (field.isRepeated()) {
+        // The underlying list object is still modifiable at this point.
+        // Make sure not to expose the modifiable list to the caller.
+        return Collections.unmodifiableList((List) object);
+      } else {
+        return object;
+      }
+    }
+
+    @Override
+    public BuilderType setField(final FieldDescriptor field, final Object value) {
+      internalGetFieldAccessorTable().getField(field).set(this, value);
+      return (BuilderType) this;
+    }
+
+    @Override
+    public BuilderType clearField(final FieldDescriptor field) {
+      internalGetFieldAccessorTable().getField(field).clear(this);
+      return (BuilderType) this;
+    }
+
+    @Override
+    public BuilderType clearOneof(final OneofDescriptor oneof) {
+      internalGetFieldAccessorTable().getOneof(oneof).clear(this);
+      return (BuilderType) this;
+    }
+
+    @Override
+    public int getRepeatedFieldCount(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field)
+          .getRepeatedCount(this);
+    }
+
+    @Override
+    public Object getRepeatedField(final FieldDescriptor field, final int index) {
+      return internalGetFieldAccessorTable().getField(field)
+          .getRepeated(this, index);
+    }
+
+    @Override
+    public BuilderType setRepeatedField(
+        final FieldDescriptor field, final int index, final Object value) {
+      internalGetFieldAccessorTable().getField(field)
+        .setRepeated(this, index, value);
+      return (BuilderType) this;
+    }
+
+    @Override
+    public BuilderType addRepeatedField(final FieldDescriptor field, final Object value) {
+      internalGetFieldAccessorTable().getField(field).addRepeated(this, value);
+      return (BuilderType) this;
+    }
+
+    @Override
+    public BuilderType setUnknownFields(final UnknownFieldSet unknownFields) {
+      this.unknownFields = unknownFields;
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    @Override
+    public BuilderType mergeUnknownFields(
+        final UnknownFieldSet unknownFields) {
+      this.unknownFields =
+        UnknownFieldSet.newBuilder(this.unknownFields)
+                       .mergeFrom(unknownFields)
+                       .build();
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    @Override
+    public boolean isInitialized() {
+      for (final FieldDescriptor field : getDescriptorForType().getFields()) {
+        // Check that all required fields are present.
+        if (field.isRequired()) {
+          if (!hasField(field)) {
+            return false;
+          }
+        }
+        // Check that embedded messages are initialized.
+        if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+          if (field.isRepeated()) {
+            @SuppressWarnings("unchecked") final
+            List<Message> messageList = (List<Message>) getField(field);
+            for (final Message element : messageList) {
+              if (!element.isInitialized()) {
+                return false;
+              }
+            }
+          } else {
+            if (hasField(field) &&
+                !((Message) getField(field)).isInitialized()) {
+              return false;
+            }
+          }
+        }
+      }
+      return true;
+    }
+
+    @Override
+    public final UnknownFieldSet getUnknownFields() {
+      return unknownFields;
+    }
+
+    /**
+     * Called by subclasses to parse an unknown field.
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    protected boolean parseUnknownField(
+        final CodedInputStream input,
+        final UnknownFieldSet.Builder unknownFields,
+        final ExtensionRegistryLite extensionRegistry,
+        final int tag) throws IOException {
+      return unknownFields.mergeFieldFrom(tag, input);
+    }
+
+    /**
+     * Implementation of {@link BuilderParent} for giving to our children. This
+     * small inner class makes it so we don't publicly expose the BuilderParent
+     * methods.
+     */
+    private class BuilderParentImpl implements BuilderParent {
+
+      @Override
+      public void markDirty() {
+        onChanged();
+      }
+    }
+
+    /**
+     * Gets the {@link BuilderParent} for giving to our children.
+     * @return The builder parent for our children.
+     */
+    protected BuilderParent getParentForChildren() {
+      if (meAsParent == null) {
+        meAsParent = new BuilderParentImpl();
+      }
+      return meAsParent;
+    }
+
+    /**
+     * Called when a the builder or one of its nested children has changed
+     * and any parent should be notified of its invalidation.
+     */
+    protected final void onChanged() {
+      if (isClean && builderParent != null) {
+        builderParent.markDirty();
+
+        // Don't keep dispatching invalidations until build is called again.
+        isClean = false;
+      }
+    }
+
+    /**
+     * Gets the map field with the given field number. This method should be
+     * overridden in the generated message class if the message contains map
+     * fields.
+     *
+     * Unlike other field types, reflection support for map fields can't be
+     * implemented based on generated public API because we need to access a
+     * map field as a list in reflection API but the generated API only allows
+     * us to access it as a map. This method returns the underlying map field
+     * directly and thus enables us to access the map field as a list.
+     */
+    @SuppressWarnings({"unused", "rawtypes"})
+    protected MapField internalGetMapField(int fieldNumber) {
+      // Note that we can't use descriptor names here because this method will
+      // be called when descriptor is being initialized.
+      throw new RuntimeException(
+          "No map fields found in " + getClass().getName());
+    }
+
+    /** Like {@link #internalGetMapField} but return a mutable version. */
+    @SuppressWarnings({"unused", "rawtypes"})
+    protected MapField internalGetMutableMapField(int fieldNumber) {
+      // Note that we can't use descriptor names here because this method will
+      // be called when descriptor is being initialized.
+      throw new RuntimeException(
+          "No map fields found in " + getClass().getName());
+    }
+  }
+
+  // =================================================================
+  // Extensions-related stuff
+
+  public interface ExtendableMessageOrBuilder<
+      MessageType extends ExtendableMessage> extends MessageOrBuilder {
+    // Re-define for return type covariance.
+    @Override
+    Message getDefaultInstanceForType();
+
+    /** Check if a singular extension is present. */
+    <Type> boolean hasExtension(
+        ExtensionLite<MessageType, Type> extension);
+
+    /** Get the number of elements in a repeated extension. */
+    <Type> int getExtensionCount(
+        ExtensionLite<MessageType, List<Type>> extension);
+
+    /** Get the value of an extension. */
+    <Type> Type getExtension(
+        ExtensionLite<MessageType, Type> extension);
+
+    /** Get one element of a repeated extension. */
+    <Type> Type getExtension(
+        ExtensionLite<MessageType, List<Type>> extension,
+        int index);
+
+    /** Check if a singular extension is present. */
+    <Type> boolean hasExtension(
+        Extension<MessageType, Type> extension);
+    /** Check if a singular extension is present. */
+    <Type> boolean hasExtension(
+        GeneratedExtension<MessageType, Type> extension);
+    /** Get the number of elements in a repeated extension. */
+    <Type> int getExtensionCount(
+        Extension<MessageType, List<Type>> extension);
+    /** Get the number of elements in a repeated extension. */
+    <Type> int getExtensionCount(
+        GeneratedExtension<MessageType, List<Type>> extension);
+    /** Get the value of an extension. */
+    <Type> Type getExtension(
+        Extension<MessageType, Type> extension);
+    /** Get the value of an extension. */
+    <Type> Type getExtension(
+        GeneratedExtension<MessageType, Type> extension);
+    /** Get one element of a repeated extension. */
+    <Type> Type getExtension(
+        Extension<MessageType, List<Type>> extension,
+        int index);
+    /** Get one element of a repeated extension. */
+    <Type> Type getExtension(
+        GeneratedExtension<MessageType, List<Type>> extension,
+        int index);
+  }
+
+  /**
+   * Generated message classes for message types that contain extension ranges
+   * subclass this.
+   *
+   * <p>This class implements type-safe accessors for extensions.  They
+   * implement all the same operations that you can do with normal fields --
+   * e.g. "has", "get", and "getCount" -- but for extensions.  The extensions
+   * are identified using instances of the class {@link GeneratedExtension};
+   * the protocol compiler generates a static instance of this class for every
+   * extension in its input.  Through the magic of generics, all is made
+   * type-safe.
+   *
+   * <p>For example, imagine you have the {@code .proto} file:
+   *
+   * <pre>
+   * option java_class = "MyProto";
+   *
+   * message Foo {
+   *   extensions 1000 to max;
+   * }
+   *
+   * extend Foo {
+   *   optional int32 bar;
+   * }
+   * </pre>
+   *
+   * <p>Then you might write code like:
+   *
+   * <pre>
+   * MyProto.Foo foo = getFoo();
+   * int i = foo.getExtension(MyProto.bar);
+   * </pre>
+   *
+   * <p>See also {@link ExtendableBuilder}.
+   */
+  public abstract static class ExtendableMessage<
+        MessageType extends ExtendableMessage>
+      extends GeneratedMessageV3
+      implements ExtendableMessageOrBuilder<MessageType> {
+
+    private static final long serialVersionUID = 1L;
+
+    private final FieldSet<FieldDescriptor> extensions;
+
+    protected ExtendableMessage() {
+      this.extensions = FieldSet.newFieldSet();
+    }
+
+    protected ExtendableMessage(
+        ExtendableBuilder<MessageType, ?> builder) {
+      super(builder);
+      this.extensions = builder.buildExtensions();
+    }
+
+    private void verifyExtensionContainingType(
+        final Extension<MessageType, ?> extension) {
+      if (extension.getDescriptor().getContainingType() !=
+          getDescriptorForType()) {
+        // This can only happen if someone uses unchecked operations.
+        throw new IllegalArgumentException(
+          "Extension is for type \"" +
+          extension.getDescriptor().getContainingType().getFullName() +
+          "\" which does not match message type \"" +
+          getDescriptorForType().getFullName() + "\".");
+      }
+    }
+
+    /** Check if a singular extension is present. */
+    @Override
+    public final <Type> boolean hasExtension(final ExtensionLite<MessageType, Type> extensionLite) {
+      Extension<MessageType, Type> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      return extensions.hasField(extension.getDescriptor());
+    }
+
+    /** Get the number of elements in a repeated extension. */
+    @Override
+    public final <Type> int getExtensionCount(
+        final ExtensionLite<MessageType, List<Type>> extensionLite) {
+      Extension<MessageType, List<Type>> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      return extensions.getRepeatedFieldCount(descriptor);
+    }
+
+    /** Get the value of an extension. */
+    @Override
+    @SuppressWarnings("unchecked")
+    public final <Type> Type getExtension(final ExtensionLite<MessageType, Type> extensionLite) {
+      Extension<MessageType, Type> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      final Object value = extensions.getField(descriptor);
+      if (value == null) {
+        if (descriptor.isRepeated()) {
+          return (Type) Collections.emptyList();
+        } else if (descriptor.getJavaType() ==
+                   FieldDescriptor.JavaType.MESSAGE) {
+          return (Type) extension.getMessageDefaultInstance();
+        } else {
+          return (Type) extension.fromReflectionType(
+              descriptor.getDefaultValue());
+        }
+      } else {
+        return (Type) extension.fromReflectionType(value);
+      }
+    }
+
+    /** Get one element of a repeated extension. */
+    @Override
+    @SuppressWarnings("unchecked")
+    public final <Type> Type getExtension(
+        final ExtensionLite<MessageType, List<Type>> extensionLite, final int index) {
+      Extension<MessageType, List<Type>> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      return (Type) extension.singularFromReflectionType(
+          extensions.getRepeatedField(descriptor, index));
+    }
+
+    /** Check if a singular extension is present. */
+    @Override
+    public final <Type> boolean hasExtension(final Extension<MessageType, Type> extension) {
+      return hasExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Check if a singular extension is present. */
+    @Override
+    public final <Type> boolean hasExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      return hasExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Get the number of elements in a repeated extension. */
+    @Override
+    public final <Type> int getExtensionCount(
+        final Extension<MessageType, List<Type>> extension) {
+      return getExtensionCount((ExtensionLite<MessageType, List<Type>>) extension);
+    }
+    /** Get the number of elements in a repeated extension. */
+    @Override
+    public final <Type> int getExtensionCount(
+        final GeneratedExtension<MessageType, List<Type>> extension) {
+      return getExtensionCount((ExtensionLite<MessageType, List<Type>>) extension);
+    }
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(final Extension<MessageType, Type> extension) {
+      return getExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      return getExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Get one element of a repeated extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final Extension<MessageType, List<Type>> extension, final int index) {
+      return getExtension((ExtensionLite<MessageType, List<Type>>) extension, index);
+    }
+    /** Get one element of a repeated extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension, final int index) {
+      return getExtension((ExtensionLite<MessageType, List<Type>>) extension, index);
+    }
+
+    /** Called by subclasses to check if all extensions are initialized. */
+    protected boolean extensionsAreInitialized() {
+      return extensions.isInitialized();
+    }
+
+    @Override
+    public boolean isInitialized() {
+      return super.isInitialized() && extensionsAreInitialized();
+    }
+
+    @Override
+    protected boolean parseUnknownField(
+        CodedInputStream input,
+        UnknownFieldSet.Builder unknownFields,
+        ExtensionRegistryLite extensionRegistry,
+        int tag) throws IOException {
+      return MessageReflection.mergeFieldFrom(
+          input, unknownFields, extensionRegistry, getDescriptorForType(),
+          new MessageReflection.ExtensionAdapter(extensions), tag);
+    }
+
+
+    /**
+     * Used by parsing constructors in generated classes.
+     */
+    @Override
+    protected void makeExtensionsImmutable() {
+      extensions.makeImmutable();
+    }
+
+    /**
+     * Used by subclasses to serialize extensions.  Extension ranges may be
+     * interleaved with field numbers, but we must write them in canonical
+     * (sorted by field number) order.  ExtensionWriter helps us write
+     * individual ranges of extensions at once.
+     */
+    protected class ExtensionWriter {
+      // Imagine how much simpler this code would be if Java iterators had
+      // a way to get the next element without advancing the iterator.
+
+      private final Iterator<Map.Entry<FieldDescriptor, Object>> iter =
+        extensions.iterator();
+      private Map.Entry<FieldDescriptor, Object> next;
+      private final boolean messageSetWireFormat;
+
+      private ExtensionWriter(final boolean messageSetWireFormat) {
+        if (iter.hasNext()) {
+          next = iter.next();
+        }
+        this.messageSetWireFormat = messageSetWireFormat;
+      }
+
+      public void writeUntil(final int end, final CodedOutputStream output)
+                             throws IOException {
+        while (next != null && next.getKey().getNumber() < end) {
+          FieldDescriptor descriptor = next.getKey();
+          if (messageSetWireFormat && descriptor.getLiteJavaType() ==
+                  WireFormat.JavaType.MESSAGE &&
+              !descriptor.isRepeated()) {
+            if (next instanceof LazyField.LazyEntry<?>) {
+              output.writeRawMessageSetExtension(descriptor.getNumber(),
+                  ((LazyField.LazyEntry<?>) next).getField().toByteString());
+            } else {
+              output.writeMessageSetExtension(descriptor.getNumber(),
+                                              (Message) next.getValue());
+            }
+          } else {
+            // TODO(xiangl): Taken care of following code, it may cause
+            // problem when we use LazyField for normal fields/extensions.
+            // Due to the optional field can be duplicated at the end of
+            // serialized bytes, which will make the serialized size change
+            // after lazy field parsed. So when we use LazyField globally,
+            // we need to change the following write method to write cached
+            // bytes directly rather than write the parsed message.
+            FieldSet.writeField(descriptor, next.getValue(), output);
+          }
+          if (iter.hasNext()) {
+            next = iter.next();
+          } else {
+            next = null;
+          }
+        }
+      }
+    }
+
+    protected ExtensionWriter newExtensionWriter() {
+      return new ExtensionWriter(false);
+    }
+    protected ExtensionWriter newMessageSetExtensionWriter() {
+      return new ExtensionWriter(true);
+    }
+
+    /** Called by subclasses to compute the size of extensions. */
+    protected int extensionsSerializedSize() {
+      return extensions.getSerializedSize();
+    }
+    protected int extensionsSerializedSizeAsMessageSet() {
+      return extensions.getMessageSetSerializedSize();
+    }
+
+    // ---------------------------------------------------------------
+    // Reflection
+
+    protected Map<FieldDescriptor, Object> getExtensionFields() {
+      return extensions.getAllFields();
+    }
+
+    @Override
+    public Map<FieldDescriptor, Object> getAllFields() {
+      final Map<FieldDescriptor, Object> result =
+          super.getAllFieldsMutable(/* getBytesForString = */ false);
+      result.putAll(getExtensionFields());
+      return Collections.unmodifiableMap(result);
+    }
+
+    @Override
+    public Map<FieldDescriptor, Object> getAllFieldsRaw() {
+      final Map<FieldDescriptor, Object> result =
+          super.getAllFieldsMutable(/* getBytesForString = */ false);
+      result.putAll(getExtensionFields());
+      return Collections.unmodifiableMap(result);
+    }
+
+    @Override
+    public boolean hasField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.hasField(field);
+      } else {
+        return super.hasField(field);
+      }
+    }
+
+    @Override
+    public Object getField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        final Object value = extensions.getField(field);
+        if (value == null) {
+          if (field.isRepeated()) {
+            return Collections.emptyList();
+          } else if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+            // Lacking an ExtensionRegistry, we have no way to determine the
+            // extension's real type, so we return a DynamicMessage.
+            return DynamicMessage.getDefaultInstance(field.getMessageType());
+          } else {
+            return field.getDefaultValue();
+          }
+        } else {
+          return value;
+        }
+      } else {
+        return super.getField(field);
+      }
+    }
+
+    @Override
+    public int getRepeatedFieldCount(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedFieldCount(field);
+      } else {
+        return super.getRepeatedFieldCount(field);
+      }
+    }
+
+    @Override
+    public Object getRepeatedField(final FieldDescriptor field,
+                                   final int index) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedField(field, index);
+      } else {
+        return super.getRepeatedField(field, index);
+      }
+    }
+
+    private void verifyContainingType(final FieldDescriptor field) {
+      if (field.getContainingType() != getDescriptorForType()) {
+        throw new IllegalArgumentException(
+          "FieldDescriptor does not match message type.");
+      }
+    }
+  }
+
+  /**
+   * Generated message builders for message types that contain extension ranges
+   * subclass this.
+   *
+   * <p>This class implements type-safe accessors for extensions.  They
+   * implement all the same operations that you can do with normal fields --
+   * e.g. "get", "set", and "add" -- but for extensions.  The extensions are
+   * identified using instances of the class {@link GeneratedExtension}; the
+   * protocol compiler generates a static instance of this class for every
+   * extension in its input.  Through the magic of generics, all is made
+   * type-safe.
+   *
+   * <p>For example, imagine you have the {@code .proto} file:
+   *
+   * <pre>
+   * option java_class = "MyProto";
+   *
+   * message Foo {
+   *   extensions 1000 to max;
+   * }
+   *
+   * extend Foo {
+   *   optional int32 bar;
+   * }
+   * </pre>
+   *
+   * <p>Then you might write code like:
+   *
+   * <pre>
+   * MyProto.Foo foo =
+   *   MyProto.Foo.newBuilder()
+   *     .setExtension(MyProto.bar, 123)
+   *     .build();
+   * </pre>
+   *
+   * <p>See also {@link ExtendableMessage}.
+   */
+  @SuppressWarnings("unchecked")
+  public abstract static class ExtendableBuilder<
+        MessageType extends ExtendableMessage,
+        BuilderType extends ExtendableBuilder<MessageType, BuilderType>>
+      extends Builder<BuilderType>
+      implements ExtendableMessageOrBuilder<MessageType> {
+
+    private FieldSet<FieldDescriptor> extensions = FieldSet.emptySet();
+
+    protected ExtendableBuilder() {}
+
+    protected ExtendableBuilder(
+        BuilderParent parent) {
+      super(parent);
+    }
+
+    // For immutable message conversion.
+    void internalSetExtensionSet(FieldSet<FieldDescriptor> extensions) {
+      this.extensions = extensions;
+    }
+
+    @Override
+    public BuilderType clear() {
+      extensions = FieldSet.emptySet();
+      return super.clear();
+    }
+
+    // This is implemented here only to work around an apparent bug in the
+    // Java compiler and/or build system.  See bug #1898463.  The mere presence
+    // of this clone() implementation makes it go away.
+    @Override
+    public BuilderType clone() {
+      return super.clone();
+    }
+
+    private void ensureExtensionsIsMutable() {
+      if (extensions.isImmutable()) {
+        extensions = extensions.clone();
+      }
+    }
+
+    private void verifyExtensionContainingType(
+        final Extension<MessageType, ?> extension) {
+      if (extension.getDescriptor().getContainingType() !=
+          getDescriptorForType()) {
+        // This can only happen if someone uses unchecked operations.
+        throw new IllegalArgumentException(
+          "Extension is for type \"" +
+          extension.getDescriptor().getContainingType().getFullName() +
+          "\" which does not match message type \"" +
+          getDescriptorForType().getFullName() + "\".");
+      }
+    }
+
+    /** Check if a singular extension is present. */
+    @Override
+    public final <Type> boolean hasExtension(final ExtensionLite<MessageType, Type> extensionLite) {
+      Extension<MessageType, Type> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      return extensions.hasField(extension.getDescriptor());
+    }
+
+    /** Get the number of elements in a repeated extension. */
+    @Override
+    public final <Type> int getExtensionCount(
+        final ExtensionLite<MessageType, List<Type>> extensionLite) {
+      Extension<MessageType, List<Type>> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      return extensions.getRepeatedFieldCount(descriptor);
+    }
+
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(final ExtensionLite<MessageType, Type> extensionLite) {
+      Extension<MessageType, Type> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      final Object value = extensions.getField(descriptor);
+      if (value == null) {
+        if (descriptor.isRepeated()) {
+          return (Type) Collections.emptyList();
+        } else if (descriptor.getJavaType() ==
+                   FieldDescriptor.JavaType.MESSAGE) {
+          return (Type) extension.getMessageDefaultInstance();
+        } else {
+          return (Type) extension.fromReflectionType(
+              descriptor.getDefaultValue());
+        }
+      } else {
+        return (Type) extension.fromReflectionType(value);
+      }
+    }
+
+    /** Get one element of a repeated extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final ExtensionLite<MessageType, List<Type>> extensionLite, final int index) {
+      Extension<MessageType, List<Type>> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      return (Type) extension.singularFromReflectionType(
+          extensions.getRepeatedField(descriptor, index));
+    }
+
+    /** Set the value of an extension. */
+    public final <Type> BuilderType setExtension(
+        final ExtensionLite<MessageType, Type> extensionLite,
+        final Type value) {
+      Extension<MessageType, Type> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      extensions.setField(descriptor, extension.toReflectionType(value));
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Set the value of one element of a repeated extension. */
+    public final <Type> BuilderType setExtension(
+        final ExtensionLite<MessageType, List<Type>> extensionLite,
+        final int index, final Type value) {
+      Extension<MessageType, List<Type>> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      extensions.setRepeatedField(
+        descriptor, index,
+        extension.singularToReflectionType(value));
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Append a value to a repeated extension. */
+    public final <Type> BuilderType addExtension(
+        final ExtensionLite<MessageType, List<Type>> extensionLite,
+        final Type value) {
+      Extension<MessageType, List<Type>> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      extensions.addRepeatedField(
+          descriptor, extension.singularToReflectionType(value));
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Clear an extension. */
+    public final <Type> BuilderType clearExtension(
+        final ExtensionLite<MessageType, ?> extensionLite) {
+      Extension<MessageType, ?> extension = checkNotLite(extensionLite);
+
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      extensions.clearField(extension.getDescriptor());
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Check if a singular extension is present. */
+    @Override
+    public final <Type> boolean hasExtension(final Extension<MessageType, Type> extension) {
+      return hasExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Check if a singular extension is present. */
+    @Override
+    public final <Type> boolean hasExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      return hasExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Get the number of elements in a repeated extension. */
+    @Override
+    public final <Type> int getExtensionCount(
+        final Extension<MessageType, List<Type>> extension) {
+      return getExtensionCount((ExtensionLite<MessageType, List<Type>>) extension);
+    }
+    /** Get the number of elements in a repeated extension. */
+    @Override
+    public final <Type> int getExtensionCount(
+        final GeneratedExtension<MessageType, List<Type>> extension) {
+      return getExtensionCount((ExtensionLite<MessageType, List<Type>>) extension);
+    }
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(final Extension<MessageType, Type> extension) {
+      return getExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      return getExtension((ExtensionLite<MessageType, Type>) extension);
+    }
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final Extension<MessageType, List<Type>> extension, final int index) {
+      return getExtension((ExtensionLite<MessageType, List<Type>>) extension, index);
+    }
+    /** Get the value of an extension. */
+    @Override
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension, final int index) {
+      return getExtension((ExtensionLite<MessageType, List<Type>>) extension, index);
+    }
+    /** Set the value of an extension. */
+    public final <Type> BuilderType setExtension(
+        final Extension<MessageType, Type> extension, final Type value) {
+      return setExtension((ExtensionLite<MessageType, Type>) extension, value);
+    }
+    /** Set the value of an extension. */
+    public <Type> BuilderType setExtension(
+        final GeneratedExtension<MessageType, Type> extension, final Type value) {
+      return setExtension((ExtensionLite<MessageType, Type>) extension, value);
+    }
+    /** Set the value of one element of a repeated extension. */
+    public final <Type> BuilderType setExtension(
+        final Extension<MessageType, List<Type>> extension,
+        final int index, final Type value) {
+      return setExtension((ExtensionLite<MessageType, List<Type>>) extension, index, value);
+    }
+    /** Set the value of one element of a repeated extension. */
+    public <Type> BuilderType setExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension,
+        final int index, final Type value) {
+      return setExtension((ExtensionLite<MessageType, List<Type>>) extension, index, value);
+    }
+    /** Append a value to a repeated extension. */
+    public final <Type> BuilderType addExtension(
+        final Extension<MessageType, List<Type>> extension, final Type value) {
+      return addExtension((ExtensionLite<MessageType, List<Type>>) extension, value);
+    }
+    /** Append a value to a repeated extension. */
+    public <Type> BuilderType addExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension, final Type value) {
+      return addExtension((ExtensionLite<MessageType, List<Type>>) extension, value);
+    }
+    /** Clear an extension. */
+    public final <Type> BuilderType clearExtension(
+        final Extension<MessageType, ?> extension) {
+      return clearExtension((ExtensionLite<MessageType, ?>) extension);
+    }
+    /** Clear an extension. */
+    public <Type> BuilderType clearExtension(
+        final GeneratedExtension<MessageType, ?> extension) {
+      return clearExtension((ExtensionLite<MessageType, ?>) extension);
+    }
+
+    /** Called by subclasses to check if all extensions are initialized. */
+    protected boolean extensionsAreInitialized() {
+      return extensions.isInitialized();
+    }
+
+    /**
+     * Called by the build code path to create a copy of the extensions for
+     * building the message.
+     */
+    private FieldSet<FieldDescriptor> buildExtensions() {
+      extensions.makeImmutable();
+      return extensions;
+    }
+
+    @Override
+    public boolean isInitialized() {
+      return super.isInitialized() && extensionsAreInitialized();
+    }
+
+    /**
+     * Called by subclasses to parse an unknown field or an extension.
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    @Override
+    protected boolean parseUnknownField(
+        final CodedInputStream input,
+        final UnknownFieldSet.Builder unknownFields,
+        final ExtensionRegistryLite extensionRegistry,
+        final int tag) throws IOException {
+      return MessageReflection.mergeFieldFrom(
+          input, unknownFields, extensionRegistry, getDescriptorForType(),
+          new MessageReflection.BuilderAdapter(this), tag);
+    }
+
+    // ---------------------------------------------------------------
+    // Reflection
+
+    @Override
+    public Map<FieldDescriptor, Object> getAllFields() {
+      final Map<FieldDescriptor, Object> result = super.getAllFieldsMutable();
+      result.putAll(extensions.getAllFields());
+      return Collections.unmodifiableMap(result);
+    }
+
+    @Override
+    public Object getField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        final Object value = extensions.getField(field);
+        if (value == null) {
+          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+            // Lacking an ExtensionRegistry, we have no way to determine the
+            // extension's real type, so we return a DynamicMessage.
+            return DynamicMessage.getDefaultInstance(field.getMessageType());
+          } else {
+            return field.getDefaultValue();
+          }
+        } else {
+          return value;
+        }
+      } else {
+        return super.getField(field);
+      }
+    }
+
+    @Override
+    public int getRepeatedFieldCount(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedFieldCount(field);
+      } else {
+        return super.getRepeatedFieldCount(field);
+      }
+    }
+
+    @Override
+    public Object getRepeatedField(final FieldDescriptor field,
+                                   final int index) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedField(field, index);
+      } else {
+        return super.getRepeatedField(field, index);
+      }
+    }
+
+    @Override
+    public boolean hasField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.hasField(field);
+      } else {
+        return super.hasField(field);
+      }
+    }
+
+    @Override
+    public BuilderType setField(final FieldDescriptor field,
+                                final Object value) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.setField(field, value);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.setField(field, value);
+      }
+    }
+
+    @Override
+    public BuilderType clearField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.clearField(field);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.clearField(field);
+      }
+    }
+
+    @Override
+    public BuilderType setRepeatedField(final FieldDescriptor field,
+                                        final int index, final Object value) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.setRepeatedField(field, index, value);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.setRepeatedField(field, index, value);
+      }
+    }
+
+    @Override
+    public BuilderType addRepeatedField(final FieldDescriptor field,
+                                        final Object value) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.addRepeatedField(field, value);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.addRepeatedField(field, value);
+      }
+    }
+
+    protected final void mergeExtensionFields(final ExtendableMessage other) {
+      ensureExtensionsIsMutable();
+      extensions.mergeFrom(other.extensions);
+      onChanged();
+    }
+
+    private void verifyContainingType(final FieldDescriptor field) {
+      if (field.getContainingType() != getDescriptorForType()) {
+        throw new IllegalArgumentException(
+          "FieldDescriptor does not match message type.");
+      }
+    }
+  }
+
+  // -----------------------------------------------------------------
+
+  /**
+   * Gets the descriptor for an extension. The implementation depends on whether
+   * the extension is scoped in the top level of a file or scoped in a Message.
+   */
+  static interface ExtensionDescriptorRetriever {
+    FieldDescriptor getDescriptor();
+  }
+
+  private abstract static class CachedDescriptorRetriever
+      implements ExtensionDescriptorRetriever {
+    private volatile FieldDescriptor descriptor;
+    protected abstract FieldDescriptor loadDescriptor();
+
+    @Override
+    public FieldDescriptor getDescriptor() {
+      if (descriptor == null) {
+        synchronized (this) {
+          if (descriptor == null) {
+            descriptor = loadDescriptor();
+          }
+        }
+      }
+      return descriptor;
+    }
+  }
+
+  // =================================================================
+
+  /** Calls Class.getMethod and throws a RuntimeException if it fails. */
+  @SuppressWarnings("unchecked")
+  private static Method getMethodOrDie(
+      final Class clazz, final String name, final Class... params) {
+    try {
+      return clazz.getMethod(name, params);
+    } catch (NoSuchMethodException e) {
+      throw new RuntimeException(
+        "Generated message class \"" + clazz.getName() +
+        "\" missing method \"" + name + "\".", e);
+    }
+  }
+
+  /** Calls invoke and throws a RuntimeException if it fails. */
+  private static Object invokeOrDie(
+      final Method method, final Object object, final Object... params) {
+    try {
+      return method.invoke(object, params);
+    } catch (IllegalAccessException e) {
+      throw new RuntimeException(
+        "Couldn't use Java reflection to implement protocol message " +
+        "reflection.", e);
+    } catch (InvocationTargetException e) {
+      final Throwable cause = e.getCause();
+      if (cause instanceof RuntimeException) {
+        throw (RuntimeException) cause;
+      } else if (cause instanceof Error) {
+        throw (Error) cause;
+      } else {
+        throw new RuntimeException(
+          "Unexpected exception thrown by generated accessor method.", cause);
+      }
+    }
+  }
+
+  /**
+   * Gets the map field with the given field number. This method should be
+   * overridden in the generated message class if the message contains map
+   * fields.
+   *
+   * Unlike other field types, reflection support for map fields can't be
+   * implemented based on generated public API because we need to access a
+   * map field as a list in reflection API but the generated API only allows
+   * us to access it as a map. This method returns the underlying map field
+   * directly and thus enables us to access the map field as a list.
+   */
+  @SuppressWarnings({"rawtypes", "unused"})
+  protected MapField internalGetMapField(int fieldNumber) {
+    // Note that we can't use descriptor names here because this method will
+    // be called when descriptor is being initialized.
+    throw new RuntimeException(
+        "No map fields found in " + getClass().getName());
+  }
+
+  /**
+   * Users should ignore this class.  This class provides the implementation
+   * with access to the fields of a message object using Java reflection.
+   */
+  public static final class FieldAccessorTable {
+
+    /**
+     * Construct a FieldAccessorTable for a particular message class.  Only
+     * one FieldAccessorTable should ever be constructed per class.
+     *
+     * @param descriptor     The type's descriptor.
+     * @param camelCaseNames The camelcase names of all fields in the message.
+     *                       These are used to derive the accessor method names.
+     * @param messageClass   The message type.
+     * @param builderClass   The builder type.
+     */
+    public FieldAccessorTable(
+        final Descriptor descriptor,
+        final String[] camelCaseNames,
+        final Class<? extends GeneratedMessageV3> messageClass,
+        final Class<? extends Builder> builderClass) {
+      this(descriptor, camelCaseNames);
+      ensureFieldAccessorsInitialized(messageClass, builderClass);
+    }
+
+    /**
+     * Construct a FieldAccessorTable for a particular message class without
+     * initializing FieldAccessors.
+     */
+    public FieldAccessorTable(
+        final Descriptor descriptor,
+        final String[] camelCaseNames) {
+      this.descriptor = descriptor;
+      this.camelCaseNames = camelCaseNames;
+      fields = new FieldAccessor[descriptor.getFields().size()];
+      oneofs = new OneofAccessor[descriptor.getOneofs().size()];
+      initialized = false;
+    }
+
+    private boolean isMapFieldEnabled(FieldDescriptor field) {
+      boolean result = true;
+      return result;
+    }
+
+    /**
+     * Ensures the field accessors are initialized. This method is thread-safe.
+     *
+     * @param messageClass   The message type.
+     * @param builderClass   The builder type.
+     * @return this
+     */
+    public FieldAccessorTable ensureFieldAccessorsInitialized(
+        Class<? extends GeneratedMessageV3> messageClass,
+        Class<? extends Builder> builderClass) {
+      if (initialized) { return this; }
+      synchronized (this) {
+        if (initialized) { return this; }
+        int fieldsSize = fields.length;
+        for (int i = 0; i < fieldsSize; i++) {
+          FieldDescriptor field = descriptor.getFields().get(i);
+          String containingOneofCamelCaseName = null;
+          if (field.getContainingOneof() != null) {
+            containingOneofCamelCaseName =
+                camelCaseNames[fieldsSize + field.getContainingOneof().getIndex()];
+          }
+          if (field.isRepeated()) {
+            if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+              if (field.isMapField() && isMapFieldEnabled(field)) {
+                fields[i] = new MapFieldAccessor(
+                    field, camelCaseNames[i], messageClass, builderClass);
+              } else {
+                fields[i] = new RepeatedMessageFieldAccessor(
+                    field, camelCaseNames[i], messageClass, builderClass);
+              }
+            } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+              fields[i] = new RepeatedEnumFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            } else {
+              fields[i] = new RepeatedFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass);
+            }
+          } else {
+            if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+              fields[i] = new SingularMessageFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass,
+                  containingOneofCamelCaseName);
+            } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+              fields[i] = new SingularEnumFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass,
+                  containingOneofCamelCaseName);
+            } else if (field.getJavaType() == FieldDescriptor.JavaType.STRING) {
+              fields[i] = new SingularStringFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass,
+                  containingOneofCamelCaseName);
+            } else {
+              fields[i] = new SingularFieldAccessor(
+                  field, camelCaseNames[i], messageClass, builderClass,
+                  containingOneofCamelCaseName);
+            }
+          }
+        }
+
+        int oneofsSize = oneofs.length;
+        for (int i = 0; i < oneofsSize; i++) {
+          oneofs[i] = new OneofAccessor(
+              descriptor, camelCaseNames[i + fieldsSize],
+              messageClass, builderClass);
+        }
+        initialized = true;
+        camelCaseNames = null;
+        return this;
+      }
+    }
+
+    private final Descriptor descriptor;
+    private final FieldAccessor[] fields;
+    private String[] camelCaseNames;
+    private final OneofAccessor[] oneofs;
+    private volatile boolean initialized;
+
+    /** Get the FieldAccessor for a particular field. */
+    private FieldAccessor getField(final FieldDescriptor field) {
+      if (field.getContainingType() != descriptor) {
+        throw new IllegalArgumentException(
+          "FieldDescriptor does not match message type.");
+      } else if (field.isExtension()) {
+        // If this type had extensions, it would subclass ExtendableMessage,
+        // which overrides the reflection interface to handle extensions.
+        throw new IllegalArgumentException(
+          "This type does not have extensions.");
+      }
+      return fields[field.getIndex()];
+    }
+
+    /** Get the OneofAccessor for a particular oneof. */
+    private OneofAccessor getOneof(final OneofDescriptor oneof) {
+      if (oneof.getContainingType() != descriptor) {
+        throw new IllegalArgumentException(
+          "OneofDescriptor does not match message type.");
+      }
+      return oneofs[oneof.getIndex()];
+    }
+
+    /**
+     * Abstract interface that provides access to a single field.  This is
+     * implemented differently depending on the field type and cardinality.
+     */
+    private interface FieldAccessor {
+      Object get(GeneratedMessageV3 message);
+      Object get(GeneratedMessageV3.Builder builder);
+      Object getRaw(GeneratedMessageV3 message);
+      Object getRaw(GeneratedMessageV3.Builder builder);
+      void set(Builder builder, Object value);
+      Object getRepeated(GeneratedMessageV3 message, int index);
+      Object getRepeated(GeneratedMessageV3.Builder builder, int index);
+      Object getRepeatedRaw(GeneratedMessageV3 message, int index);
+      Object getRepeatedRaw(GeneratedMessageV3.Builder builder, int index);
+      void setRepeated(Builder builder,
+                       int index, Object value);
+      void addRepeated(Builder builder, Object value);
+      boolean has(GeneratedMessageV3 message);
+      boolean has(GeneratedMessageV3.Builder builder);
+      int getRepeatedCount(GeneratedMessageV3 message);
+      int getRepeatedCount(GeneratedMessageV3.Builder builder);
+      void clear(Builder builder);
+      Message.Builder newBuilder();
+      Message.Builder getBuilder(GeneratedMessageV3.Builder builder);
+      Message.Builder getRepeatedBuilder(GeneratedMessageV3.Builder builder,
+                                         int index);
+    }
+
+    /** OneofAccessor provides access to a single oneof. */
+    private static class OneofAccessor {
+      OneofAccessor(
+          final Descriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass) {
+        this.descriptor = descriptor;
+        caseMethod =
+            getMethodOrDie(messageClass, "get" + camelCaseName + "Case");
+        caseMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName + "Case");
+        clearMethod = getMethodOrDie(builderClass, "clear" + camelCaseName);
+      }
+
+      private final Descriptor descriptor;
+      private final Method caseMethod;
+      private final Method caseMethodBuilder;
+      private final Method clearMethod;
+
+      public boolean has(final GeneratedMessageV3 message) {
+        if (((Internal.EnumLite) invokeOrDie(caseMethod, message)).getNumber() == 0) {
+          return false;
+        }
+        return true;
+      }
+
+      public boolean has(GeneratedMessageV3.Builder builder) {
+        if (((Internal.EnumLite) invokeOrDie(caseMethodBuilder, builder)).getNumber() == 0) {
+          return false;
+        }
+        return true;
+      }
+
+      public FieldDescriptor get(final GeneratedMessageV3 message) {
+        int fieldNumber = ((Internal.EnumLite) invokeOrDie(caseMethod, message)).getNumber();
+        if (fieldNumber > 0) {
+          return descriptor.findFieldByNumber(fieldNumber);
+        }
+        return null;
+      }
+
+      public FieldDescriptor get(GeneratedMessageV3.Builder builder) {
+        int fieldNumber = ((Internal.EnumLite) invokeOrDie(caseMethodBuilder, builder)).getNumber();
+        if (fieldNumber > 0) {
+          return descriptor.findFieldByNumber(fieldNumber);
+        }
+        return null;
+      }
+
+      public void clear(final Builder builder) {
+        invokeOrDie(clearMethod, builder);
+      }
+    }
+
+    private static boolean supportFieldPresence(FileDescriptor file) {
+      return file.getSyntax() == FileDescriptor.Syntax.PROTO2;
+    }
+
+    // ---------------------------------------------------------------
+
+    private static class SingularFieldAccessor implements FieldAccessor {
+      SingularFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass,
+          final String containingOneofCamelCaseName) {
+        field = descriptor;
+        isOneofField = descriptor.getContainingOneof() != null;
+        hasHasMethod = supportFieldPresence(descriptor.getFile())
+            || (!isOneofField && descriptor.getJavaType() == FieldDescriptor.JavaType.MESSAGE);
+        getMethod = getMethodOrDie(messageClass, "get" + camelCaseName);
+        getMethodBuilder = getMethodOrDie(builderClass, "get" + camelCaseName);
+        type = getMethod.getReturnType();
+        setMethod = getMethodOrDie(builderClass, "set" + camelCaseName, type);
+        hasMethod =
+            hasHasMethod ? getMethodOrDie(messageClass, "has" + camelCaseName) : null;
+        hasMethodBuilder =
+            hasHasMethod ? getMethodOrDie(builderClass, "has" + camelCaseName) : null;
+        clearMethod = getMethodOrDie(builderClass, "clear" + camelCaseName);
+        caseMethod = isOneofField ? getMethodOrDie(
+            messageClass, "get" + containingOneofCamelCaseName + "Case") : null;
+        caseMethodBuilder = isOneofField ? getMethodOrDie(
+            builderClass, "get" + containingOneofCamelCaseName + "Case") : null;
+      }
+
+      // Note:  We use Java reflection to call public methods rather than
+      //   access private fields directly as this avoids runtime security
+      //   checks.
+      protected final Class<?> type;
+      protected final Method getMethod;
+      protected final Method getMethodBuilder;
+      protected final Method setMethod;
+      protected final Method hasMethod;
+      protected final Method hasMethodBuilder;
+      protected final Method clearMethod;
+      protected final Method caseMethod;
+      protected final Method caseMethodBuilder;
+      protected final FieldDescriptor field;
+      protected final boolean isOneofField;
+      protected final boolean hasHasMethod;
+
+      private int getOneofFieldNumber(final GeneratedMessageV3 message) {
+        return ((Internal.EnumLite) invokeOrDie(caseMethod, message)).getNumber();
+      }
+
+      private int getOneofFieldNumber(final GeneratedMessageV3.Builder builder) {
+        return ((Internal.EnumLite) invokeOrDie(caseMethodBuilder, builder)).getNumber();
+      }
+
+      @Override
+      public Object get(final GeneratedMessageV3 message) {
+        return invokeOrDie(getMethod, message);
+      }
+      @Override
+      public Object get(GeneratedMessageV3.Builder builder) {
+        return invokeOrDie(getMethodBuilder, builder);
+      }
+      @Override
+      public Object getRaw(final GeneratedMessageV3 message) {
+        return get(message);
+      }
+      @Override
+      public Object getRaw(GeneratedMessageV3.Builder builder) {
+        return get(builder);
+      }
+      @Override
+      public void set(final Builder builder, final Object value) {
+        invokeOrDie(setMethod, builder, value);
+      }
+      @Override
+      public Object getRepeated(final GeneratedMessageV3 message, final int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedField() called on a singular field.");
+      }
+      @Override
+      public Object getRepeatedRaw(final GeneratedMessageV3 message, final int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldRaw() called on a singular field.");
+      }
+      @Override
+      public Object getRepeated(GeneratedMessageV3.Builder builder, int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedField() called on a singular field.");
+      }
+      @Override
+      public Object getRepeatedRaw(GeneratedMessageV3.Builder builder, int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldRaw() called on a singular field.");
+      }
+      @Override
+      public void setRepeated(final Builder builder, final int index, final Object value) {
+        throw new UnsupportedOperationException(
+          "setRepeatedField() called on a singular field.");
+      }
+      @Override
+      public void addRepeated(final Builder builder, final Object value) {
+        throw new UnsupportedOperationException(
+          "addRepeatedField() called on a singular field.");
+      }
+      @Override
+      public boolean has(final GeneratedMessageV3 message) {
+        if (!hasHasMethod) {
+          if (isOneofField) {
+            return getOneofFieldNumber(message) == field.getNumber();
+          }
+          return !get(message).equals(field.getDefaultValue());
+        }
+        return (Boolean) invokeOrDie(hasMethod, message);
+      }
+      @Override
+      public boolean has(GeneratedMessageV3.Builder builder) {
+        if (!hasHasMethod) {
+          if (isOneofField) {
+            return getOneofFieldNumber(builder) == field.getNumber();
+          }
+          return !get(builder).equals(field.getDefaultValue());
+        }
+        return (Boolean) invokeOrDie(hasMethodBuilder, builder);
+      }
+      @Override
+      public int getRepeatedCount(final GeneratedMessageV3 message) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldSize() called on a singular field.");
+      }
+      @Override
+      public int getRepeatedCount(GeneratedMessageV3.Builder builder) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldSize() called on a singular field.");
+      }
+      @Override
+      public void clear(final Builder builder) {
+        invokeOrDie(clearMethod, builder);
+      }
+      @Override
+      public Message.Builder newBuilder() {
+        throw new UnsupportedOperationException(
+          "newBuilderForField() called on a non-Message type.");
+      }
+      @Override
+      public Message.Builder getBuilder(GeneratedMessageV3.Builder builder) {
+        throw new UnsupportedOperationException(
+          "getFieldBuilder() called on a non-Message type.");
+      }
+      @Override
+      public Message.Builder getRepeatedBuilder(GeneratedMessageV3.Builder builder, int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldBuilder() called on a non-Message type.");
+      }
+    }
+
+    private static class RepeatedFieldAccessor implements FieldAccessor {
+      protected final Class type;
+      protected final Method getMethod;
+      protected final Method getMethodBuilder;
+      protected final Method getRepeatedMethod;
+      protected final Method getRepeatedMethodBuilder;
+      protected final Method setRepeatedMethod;
+      protected final Method addRepeatedMethod;
+      protected final Method getCountMethod;
+      protected final Method getCountMethodBuilder;
+      protected final Method clearMethod;
+
+      RepeatedFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass) {
+        getMethod = getMethodOrDie(messageClass,
+                                   "get" + camelCaseName + "List");
+        getMethodBuilder = getMethodOrDie(builderClass,
+                                   "get" + camelCaseName + "List");
+        getRepeatedMethod =
+            getMethodOrDie(messageClass, "get" + camelCaseName, Integer.TYPE);
+        getRepeatedMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName, Integer.TYPE);
+        type = getRepeatedMethod.getReturnType();
+        setRepeatedMethod =
+            getMethodOrDie(builderClass, "set" + camelCaseName,
+                           Integer.TYPE, type);
+        addRepeatedMethod =
+            getMethodOrDie(builderClass, "add" + camelCaseName, type);
+        getCountMethod =
+            getMethodOrDie(messageClass, "get" + camelCaseName + "Count");
+        getCountMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName + "Count");
+
+        clearMethod = getMethodOrDie(builderClass, "clear" + camelCaseName);
+      }
+
+      @Override
+      public Object get(final GeneratedMessageV3 message) {
+        return invokeOrDie(getMethod, message);
+      }
+      @Override
+      public Object get(GeneratedMessageV3.Builder builder) {
+        return invokeOrDie(getMethodBuilder, builder);
+      }
+      @Override
+      public Object getRaw(final GeneratedMessageV3 message) {
+        return get(message);
+      }
+      @Override
+      public Object getRaw(GeneratedMessageV3.Builder builder) {
+        return get(builder);
+      }
+      @Override
+      public void set(final Builder builder, final Object value) {
+        // Add all the elements individually.  This serves two purposes:
+        // 1) Verifies that each element has the correct type.
+        // 2) Insures that the caller cannot modify the list later on and
+        //    have the modifications be reflected in the message.
+        clear(builder);
+        for (final Object element : (List<?>) value) {
+          addRepeated(builder, element);
+        }
+      }
+      @Override
+      public Object getRepeated(final GeneratedMessageV3 message, final int index) {
+        return invokeOrDie(getRepeatedMethod, message, index);
+      }
+      @Override
+      public Object getRepeated(GeneratedMessageV3.Builder builder, int index) {
+        return invokeOrDie(getRepeatedMethodBuilder, builder, index);
+      }
+      @Override
+      public Object getRepeatedRaw(GeneratedMessageV3 message, int index) {
+        return getRepeated(message, index);
+      }
+      @Override
+      public Object getRepeatedRaw(GeneratedMessageV3.Builder builder, int index) {
+        return getRepeated(builder, index);
+      }
+      @Override
+      public void setRepeated(final Builder builder, final int index, final Object value) {
+        invokeOrDie(setRepeatedMethod, builder, index, value);
+      }
+      @Override
+      public void addRepeated(final Builder builder, final Object value) {
+        invokeOrDie(addRepeatedMethod, builder, value);
+      }
+      @Override
+      public boolean has(final GeneratedMessageV3 message) {
+        throw new UnsupportedOperationException(
+          "hasField() called on a repeated field.");
+      }
+      @Override
+      public boolean has(GeneratedMessageV3.Builder builder) {
+        throw new UnsupportedOperationException(
+          "hasField() called on a repeated field.");
+      }
+      @Override
+      public int getRepeatedCount(final GeneratedMessageV3 message) {
+        return (Integer) invokeOrDie(getCountMethod, message);
+      }
+      @Override
+      public int getRepeatedCount(GeneratedMessageV3.Builder builder) {
+        return (Integer) invokeOrDie(getCountMethodBuilder, builder);
+      }
+      @Override
+      public void clear(final Builder builder) {
+        invokeOrDie(clearMethod, builder);
+      }
+      @Override
+      public Message.Builder newBuilder() {
+        throw new UnsupportedOperationException(
+          "newBuilderForField() called on a non-Message type.");
+      }
+      @Override
+      public Message.Builder getBuilder(GeneratedMessageV3.Builder builder) {
+        throw new UnsupportedOperationException(
+          "getFieldBuilder() called on a non-Message type.");
+      }
+      @Override
+      public Message.Builder getRepeatedBuilder(GeneratedMessageV3.Builder builder, int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldBuilder() called on a non-Message type.");
+      }
+    }
+
+    private static class MapFieldAccessor implements FieldAccessor {
+      MapFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass) {
+        field = descriptor;
+        Method getDefaultInstanceMethod =
+            getMethodOrDie(messageClass, "getDefaultInstance");
+        MapField defaultMapField = getMapField(
+            (GeneratedMessageV3) invokeOrDie(getDefaultInstanceMethod, null));
+        mapEntryMessageDefaultInstance =
+            defaultMapField.getMapEntryMessageDefaultInstance();
+      }
+
+      private final FieldDescriptor field;
+      private final Message mapEntryMessageDefaultInstance;
+
+      private MapField<?, ?> getMapField(GeneratedMessageV3 message) {
+        return (MapField<?, ?>) message.internalGetMapField(field.getNumber());
+      }
+
+      private MapField<?, ?> getMapField(GeneratedMessageV3.Builder builder) {
+        return (MapField<?, ?>) builder.internalGetMapField(field.getNumber());
+      }
+
+      private MapField<?, ?> getMutableMapField(
+          GeneratedMessageV3.Builder builder) {
+        return (MapField<?, ?>) builder.internalGetMutableMapField(
+            field.getNumber());
+      }
+
+      @Override
+      public Object get(GeneratedMessageV3 message) {
+        List result = new ArrayList();
+        for (int i = 0; i < getRepeatedCount(message); i++) {
+          result.add(getRepeated(message, i));
+        }
+        return Collections.unmodifiableList(result);
+      }
+
+      @Override
+      public Object get(Builder builder) {
+        List result = new ArrayList();
+        for (int i = 0; i < getRepeatedCount(builder); i++) {
+          result.add(getRepeated(builder, i));
+        }
+        return Collections.unmodifiableList(result);
+      }
+
+      @Override
+      public Object getRaw(GeneratedMessageV3 message) {
+        return get(message);
+      }
+
+      @Override
+      public Object getRaw(GeneratedMessageV3.Builder builder) {
+        return get(builder);
+      }
+
+      @Override
+      public void set(Builder builder, Object value) {
+        clear(builder);
+        for (Object entry : (List) value) {
+          addRepeated(builder, entry);
+        }
+      }
+
+      @Override
+      public Object getRepeated(GeneratedMessageV3 message, int index) {
+        return getMapField(message).getList().get(index);
+      }
+
+      @Override
+      public Object getRepeated(Builder builder, int index) {
+        return getMapField(builder).getList().get(index);
+      }
+
+      @Override
+      public Object getRepeatedRaw(GeneratedMessageV3 message, int index) {
+        return getRepeated(message, index);
+      }
+
+      @Override
+      public Object getRepeatedRaw(Builder builder, int index) {
+        return getRepeated(builder, index);
+      }
+
+      @Override
+      public void setRepeated(Builder builder, int index, Object value) {
+        getMutableMapField(builder).getMutableList().set(index, (Message) value);
+      }
+
+      @Override
+      public void addRepeated(Builder builder, Object value) {
+        getMutableMapField(builder).getMutableList().add((Message) value);
+      }
+
+      @Override
+      public boolean has(GeneratedMessageV3 message) {
+        throw new UnsupportedOperationException(
+            "hasField() is not supported for repeated fields.");
+      }
+
+      @Override
+      public boolean has(Builder builder) {
+        throw new UnsupportedOperationException(
+            "hasField() is not supported for repeated fields.");
+      }
+
+      @Override
+      public int getRepeatedCount(GeneratedMessageV3 message) {
+        return getMapField(message).getList().size();
+      }
+
+      @Override
+      public int getRepeatedCount(Builder builder) {
+        return getMapField(builder).getList().size();
+      }
+
+      @Override
+      public void clear(Builder builder) {
+        getMutableMapField(builder).getMutableList().clear();
+      }
+
+      @Override
+      public com.google.protobuf.Message.Builder newBuilder() {
+        return mapEntryMessageDefaultInstance.newBuilderForType();
+      }
+
+      @Override
+      public com.google.protobuf.Message.Builder getBuilder(Builder builder) {
+        throw new UnsupportedOperationException(
+            "Nested builder not supported for map fields.");
+      }
+
+      @Override
+      public com.google.protobuf.Message.Builder getRepeatedBuilder(Builder builder, int index) {
+        throw new UnsupportedOperationException(
+            "Nested builder not supported for map fields.");
+      }
+    }
+
+    // ---------------------------------------------------------------
+
+    private static final class SingularEnumFieldAccessor
+        extends SingularFieldAccessor {
+      SingularEnumFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass,
+          final String containingOneofCamelCaseName) {
+        super(descriptor, camelCaseName, messageClass, builderClass, containingOneofCamelCaseName);
+
+        enumDescriptor = descriptor.getEnumType();
+
+        valueOfMethod = getMethodOrDie(type, "valueOf",
+                                       EnumValueDescriptor.class);
+        getValueDescriptorMethod =
+          getMethodOrDie(type, "getValueDescriptor");
+
+        supportUnknownEnumValue = descriptor.getFile().supportsUnknownEnumValue();
+        if (supportUnknownEnumValue) {
+          getValueMethod =
+              getMethodOrDie(messageClass, "get" + camelCaseName + "Value");
+          getValueMethodBuilder =
+              getMethodOrDie(builderClass, "get" + camelCaseName + "Value");
+          setValueMethod =
+              getMethodOrDie(builderClass, "set" + camelCaseName + "Value", int.class);
+        }
+      }
+
+      private EnumDescriptor enumDescriptor;
+
+      private Method valueOfMethod;
+      private Method getValueDescriptorMethod;
+
+      private boolean supportUnknownEnumValue;
+      private Method getValueMethod;
+      private Method getValueMethodBuilder;
+      private Method setValueMethod;
+
+      @Override
+      public Object get(final GeneratedMessageV3 message) {
+        if (supportUnknownEnumValue) {
+          int value = (Integer) invokeOrDie(getValueMethod, message);
+          return enumDescriptor.findValueByNumberCreatingIfUnknown(value);
+        }
+        return invokeOrDie(getValueDescriptorMethod, super.get(message));
+      }
+
+      @Override
+      public Object get(final GeneratedMessageV3.Builder builder) {
+        if (supportUnknownEnumValue) {
+          int value = (Integer) invokeOrDie(getValueMethodBuilder, builder);
+          return enumDescriptor.findValueByNumberCreatingIfUnknown(value);
+        }
+        return invokeOrDie(getValueDescriptorMethod, super.get(builder));
+      }
+
+      @Override
+      public void set(final Builder builder, final Object value) {
+        if (supportUnknownEnumValue) {
+          invokeOrDie(setValueMethod, builder,
+              ((EnumValueDescriptor) value).getNumber());
+          return;
+        }
+        super.set(builder, invokeOrDie(valueOfMethod, null, value));
+      }
+    }
+
+    private static final class RepeatedEnumFieldAccessor
+        extends RepeatedFieldAccessor {
+      RepeatedEnumFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass) {
+        super(descriptor, camelCaseName, messageClass, builderClass);
+
+        enumDescriptor = descriptor.getEnumType();
+
+        valueOfMethod = getMethodOrDie(type, "valueOf",
+                                       EnumValueDescriptor.class);
+        getValueDescriptorMethod =
+          getMethodOrDie(type, "getValueDescriptor");
+
+        supportUnknownEnumValue = descriptor.getFile().supportsUnknownEnumValue();
+        if (supportUnknownEnumValue) {
+          getRepeatedValueMethod =
+              getMethodOrDie(messageClass, "get" + camelCaseName + "Value", int.class);
+          getRepeatedValueMethodBuilder =
+              getMethodOrDie(builderClass, "get" + camelCaseName + "Value", int.class);
+          setRepeatedValueMethod =
+              getMethodOrDie(builderClass, "set" + camelCaseName + "Value", int.class, int.class);
+          addRepeatedValueMethod =
+              getMethodOrDie(builderClass, "add" + camelCaseName + "Value", int.class);
+        }
+      }
+      private EnumDescriptor enumDescriptor;
+
+      private final Method valueOfMethod;
+      private final Method getValueDescriptorMethod;
+
+      private boolean supportUnknownEnumValue;
+      private Method getRepeatedValueMethod;
+      private Method getRepeatedValueMethodBuilder;
+      private Method setRepeatedValueMethod;
+      private Method addRepeatedValueMethod;
+
+      @Override
+      @SuppressWarnings("unchecked")
+      public Object get(final GeneratedMessageV3 message) {
+        final List newList = new ArrayList();
+        final int size = getRepeatedCount(message);
+        for (int i = 0; i < size; i++) {
+          newList.add(getRepeated(message, i));
+        }
+        return Collections.unmodifiableList(newList);
+      }
+
+      @Override
+      @SuppressWarnings("unchecked")
+      public Object get(final GeneratedMessageV3.Builder builder) {
+        final List newList = new ArrayList();
+        final int size = getRepeatedCount(builder);
+        for (int i = 0; i < size; i++) {
+          newList.add(getRepeated(builder, i));
+        }
+        return Collections.unmodifiableList(newList);
+      }
+
+      @Override
+      public Object getRepeated(final GeneratedMessageV3 message,
+                                final int index) {
+        if (supportUnknownEnumValue) {
+          int value = (Integer) invokeOrDie(getRepeatedValueMethod, message, index);
+          return enumDescriptor.findValueByNumberCreatingIfUnknown(value);
+        }
+        return invokeOrDie(getValueDescriptorMethod,
+          super.getRepeated(message, index));
+      }
+      @Override
+      public Object getRepeated(final GeneratedMessageV3.Builder builder,
+                                final int index) {
+        if (supportUnknownEnumValue) {
+          int value = (Integer) invokeOrDie(getRepeatedValueMethodBuilder, builder, index);
+          return enumDescriptor.findValueByNumberCreatingIfUnknown(value);
+        }
+        return invokeOrDie(getValueDescriptorMethod,
+          super.getRepeated(builder, index));
+      }
+      @Override
+      public void setRepeated(final Builder builder,
+                              final int index, final Object value) {
+        if (supportUnknownEnumValue) {
+          invokeOrDie(setRepeatedValueMethod, builder, index,
+              ((EnumValueDescriptor) value).getNumber());
+          return;
+        }
+        super.setRepeated(builder, index, invokeOrDie(valueOfMethod, null,
+                          value));
+      }
+      @Override
+      public void addRepeated(final Builder builder, final Object value) {
+        if (supportUnknownEnumValue) {
+          invokeOrDie(addRepeatedValueMethod, builder,
+              ((EnumValueDescriptor) value).getNumber());
+          return;
+        }
+        super.addRepeated(builder, invokeOrDie(valueOfMethod, null, value));
+      }
+    }
+
+    // ---------------------------------------------------------------
+
+    /**
+     * Field accessor for string fields.
+     *
+     * <p>This class makes getFooBytes() and setFooBytes() available for
+     * reflection API so that reflection based serialize/parse functions can
+     * access the raw bytes of the field to preserve non-UTF8 bytes in the
+     * string.
+     *
+     * <p>This ensures the serialize/parse round-trip safety, which is important
+     * for servers which forward messages.
+     */
+    private static final class SingularStringFieldAccessor
+        extends SingularFieldAccessor {
+      SingularStringFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass,
+          final String containingOneofCamelCaseName) {
+        super(descriptor, camelCaseName, messageClass, builderClass,
+            containingOneofCamelCaseName);
+        getBytesMethod = getMethodOrDie(messageClass,
+            "get" + camelCaseName + "Bytes");
+        getBytesMethodBuilder = getMethodOrDie(builderClass,
+            "get" + camelCaseName + "Bytes");
+        setBytesMethodBuilder = getMethodOrDie(builderClass,
+            "set" + camelCaseName + "Bytes", ByteString.class);
+      }
+
+      private final Method getBytesMethod;
+      private final Method getBytesMethodBuilder;
+      private final Method setBytesMethodBuilder;
+
+      @Override
+      public Object getRaw(final GeneratedMessageV3 message) {
+        return invokeOrDie(getBytesMethod, message);
+      }
+
+      @Override
+      public Object getRaw(GeneratedMessageV3.Builder builder) {
+        return invokeOrDie(getBytesMethodBuilder, builder);
+      }
+
+      @Override
+      public void set(GeneratedMessageV3.Builder builder, Object value) {
+        if (value instanceof ByteString) {
+          invokeOrDie(setBytesMethodBuilder, builder, value);
+        } else {
+          super.set(builder, value);
+        }
+      }
+    }
+
+    // ---------------------------------------------------------------
+
+    private static final class SingularMessageFieldAccessor
+        extends SingularFieldAccessor {
+      SingularMessageFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass,
+          final String containingOneofCamelCaseName) {
+        super(descriptor, camelCaseName, messageClass, builderClass,
+            containingOneofCamelCaseName);
+
+        newBuilderMethod = getMethodOrDie(type, "newBuilder");
+        getBuilderMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName + "Builder");
+      }
+
+      private final Method newBuilderMethod;
+      private final Method getBuilderMethodBuilder;
+
+      private Object coerceType(final Object value) {
+        if (type.isInstance(value)) {
+          return value;
+        } else {
+          // The value is not the exact right message type.  However, if it
+          // is an alternative implementation of the same type -- e.g. a
+          // DynamicMessage -- we should accept it.  In this case we can make
+          // a copy of the message.
+          return ((Message.Builder) invokeOrDie(newBuilderMethod, null))
+                  .mergeFrom((Message) value).buildPartial();
+        }
+      }
+
+      @Override
+      public void set(final Builder builder, final Object value) {
+        super.set(builder, coerceType(value));
+      }
+      @Override
+      public Message.Builder newBuilder() {
+        return (Message.Builder) invokeOrDie(newBuilderMethod, null);
+      }
+      @Override
+      public Message.Builder getBuilder(GeneratedMessageV3.Builder builder) {
+        return (Message.Builder) invokeOrDie(getBuilderMethodBuilder, builder);
+      }
+    }
+
+    private static final class RepeatedMessageFieldAccessor
+        extends RepeatedFieldAccessor {
+      RepeatedMessageFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessageV3> messageClass,
+          final Class<? extends Builder> builderClass) {
+        super(descriptor, camelCaseName, messageClass, builderClass);
+
+        newBuilderMethod = getMethodOrDie(type, "newBuilder");
+        getBuilderMethodBuilder = getMethodOrDie(builderClass,
+            "get" + camelCaseName + "Builder", Integer.TYPE);
+      }
+
+      private final Method newBuilderMethod;
+      private final Method getBuilderMethodBuilder;
+
+      private Object coerceType(final Object value) {
+        if (type.isInstance(value)) {
+          return value;
+        } else {
+          // The value is not the exact right message type.  However, if it
+          // is an alternative implementation of the same type -- e.g. a
+          // DynamicMessage -- we should accept it.  In this case we can make
+          // a copy of the message.
+          return ((Message.Builder) invokeOrDie(newBuilderMethod, null))
+                  .mergeFrom((Message) value).build();
+        }
+      }
+
+      @Override
+      public void setRepeated(final Builder builder,
+                              final int index, final Object value) {
+        super.setRepeated(builder, index, coerceType(value));
+      }
+      @Override
+      public void addRepeated(final Builder builder, final Object value) {
+        super.addRepeated(builder, coerceType(value));
+      }
+      @Override
+      public Message.Builder newBuilder() {
+        return (Message.Builder) invokeOrDie(newBuilderMethod, null);
+      }
+      @Override
+      public Message.Builder getRepeatedBuilder(
+          final GeneratedMessageV3.Builder builder, final int index) {
+        return (Message.Builder) invokeOrDie(
+            getBuilderMethodBuilder, builder, index);
+      }
+    }
+  }
+
+  /**
+   * Replaces this object in the output stream with a serialized form.
+   * Part of Java's serialization magic.  Generated sub-classes must override
+   * this method by calling {@code return super.writeReplace();}
+   * @return a SerializedForm of this message
+   */
+  protected Object writeReplace() throws ObjectStreamException {
+    return new GeneratedMessageLite.SerializedForm(this);
+  }
+
+  /**
+   * Checks that the {@link Extension} is non-Lite and returns it as a
+   * {@link GeneratedExtension}.
+   */
+  private static <MessageType extends ExtendableMessage<MessageType>, T>
+    Extension<MessageType, T> checkNotLite(
+        ExtensionLite<MessageType, T> extension) {
+    if (extension.isLite()) {
+      throw new IllegalArgumentException("Expected non-lite extension.");
+    }
+
+    return (Extension<MessageType, T>) extension;
+  }
+  
+  protected static int computeStringSize(final int fieldNumber, final Object value) {
+    if (value instanceof String) {
+      return CodedOutputStream.computeStringSize(fieldNumber, (String) value);
+    } else {
+      return CodedOutputStream.computeBytesSize(fieldNumber, (ByteString) value);
+    }
+  }
+  
+  protected static int computeStringSizeNoTag(final Object value) {
+    if (value instanceof String) {
+      return CodedOutputStream.computeStringSizeNoTag((String) value);
+    } else {
+      return CodedOutputStream.computeBytesSizeNoTag((ByteString) value);
+    }
+  }
+  
+  protected static void writeString(
+      CodedOutputStream output, final int fieldNumber, final Object value) throws IOException {
+    if (value instanceof String) {
+      output.writeString(fieldNumber, (String) value);
+    } else {
+      output.writeBytes(fieldNumber, (ByteString) value);
+    }
+  }
+  
+  protected static void writeStringNoTag(
+      CodedOutputStream output, final Object value) throws IOException {
+    if (value instanceof String) {
+      output.writeStringNoTag((String) value);
+    } else {
+      output.writeBytesNoTag((ByteString) value);
+    }
+  }
+}
diff --git a/java/core/src/test/java/com/google/protobuf/GeneratedMessageTest.java b/java/core/src/test/java/com/google/protobuf/GeneratedMessageTest.java
index a9b8b638..127e06fd 100644
--- a/java/core/src/test/java/com/google/protobuf/GeneratedMessageTest.java
+++ b/java/core/src/test/java/com/google/protobuf/GeneratedMessageTest.java
@@ -972,7 +972,7 @@ public class GeneratedMessageTest extends TestCase {
     TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
 
     TestAllTypes.Builder builder = (TestAllTypes.Builder)
-        ((GeneratedMessage) TestAllTypes.getDefaultInstance()).
+        ((AbstractMessage) TestAllTypes.getDefaultInstance()).
             newBuilderForType(mockParent);
     builder.setOptionalInt32(1);
     builder.setOptionalNestedEnum(TestAllTypes.NestedEnum.BAR);
@@ -1027,7 +1027,7 @@ public class GeneratedMessageTest extends TestCase {
     TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
 
     TestAllExtensions.Builder builder = (TestAllExtensions.Builder)
-        ((GeneratedMessage) TestAllExtensions.getDefaultInstance()).
+        ((AbstractMessage) TestAllExtensions.getDefaultInstance()).
             newBuilderForType(mockParent);
 
     builder.addExtension(UnittestProto.repeatedInt32Extension, 1);
diff --git a/java/core/src/test/java/com/google/protobuf/RepeatedFieldBuilderTest.java b/java/core/src/test/java/com/google/protobuf/RepeatedFieldBuilderTest.java
deleted file mode 100644
index 49d52321..00000000
--- a/java/core/src/test/java/com/google/protobuf/RepeatedFieldBuilderTest.java
+++ /dev/null
@@ -1,190 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-package com.google.protobuf;
-
-import protobuf_unittest.UnittestProto.TestAllTypes;
-import protobuf_unittest.UnittestProto.TestAllTypesOrBuilder;
-
-import junit.framework.TestCase;
-
-import java.util.Collections;
-import java.util.List;
-
-/**
- * Tests for {@link RepeatedFieldBuilder}. This tests basic functionality.
- * More extensive testing is provided via other tests that exercise the
- * builder.
- *
- * @author jonp@google.com (Jon Perlow)
- */
-public class RepeatedFieldBuilderTest extends TestCase {
-
-  public void testBasicUse() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    RepeatedFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder = newRepeatedFieldBuilder(mockParent);
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(0).build());
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(1).build());
-    assertEquals(0, builder.getMessage(0).getOptionalInt32());
-    assertEquals(1, builder.getMessage(1).getOptionalInt32());
-
-    List<TestAllTypes> list = builder.build();
-    assertEquals(2, list.size());
-    assertEquals(0, list.get(0).getOptionalInt32());
-    assertEquals(1, list.get(1).getOptionalInt32());
-    assertIsUnmodifiable(list);
-
-    // Make sure it doesn't change.
-    List<TestAllTypes> list2 = builder.build();
-    assertSame(list, list2);
-    assertEquals(0, mockParent.getInvalidationCount());
-  }
-
-  public void testGoingBackAndForth() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    RepeatedFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder = newRepeatedFieldBuilder(mockParent);
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(0).build());
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(1).build());
-    assertEquals(0, builder.getMessage(0).getOptionalInt32());
-    assertEquals(1, builder.getMessage(1).getOptionalInt32());
-
-    // Convert to list
-    List<TestAllTypes> list = builder.build();
-    assertEquals(2, list.size());
-    assertEquals(0, list.get(0).getOptionalInt32());
-    assertEquals(1, list.get(1).getOptionalInt32());
-    assertIsUnmodifiable(list);
-
-    // Update 0th item
-    assertEquals(0, mockParent.getInvalidationCount());
-    builder.getBuilder(0).setOptionalString("foo");
-    assertEquals(1, mockParent.getInvalidationCount());
-    list = builder.build();
-    assertEquals(2, list.size());
-    assertEquals(0, list.get(0).getOptionalInt32());
-      assertEquals("foo", list.get(0).getOptionalString());
-    assertEquals(1, list.get(1).getOptionalInt32());
-    assertIsUnmodifiable(list);
-    assertEquals(1, mockParent.getInvalidationCount());
-  }
-
-  public void testVariousMethods() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    RepeatedFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder = newRepeatedFieldBuilder(mockParent);
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(1).build());
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(2).build());
-    builder.addBuilder(0, TestAllTypes.getDefaultInstance())
-        .setOptionalInt32(0);
-    builder.addBuilder(TestAllTypes.getDefaultInstance()).setOptionalInt32(3);
-
-    assertEquals(0, builder.getMessage(0).getOptionalInt32());
-    assertEquals(1, builder.getMessage(1).getOptionalInt32());
-    assertEquals(2, builder.getMessage(2).getOptionalInt32());
-    assertEquals(3, builder.getMessage(3).getOptionalInt32());
-
-    assertEquals(0, mockParent.getInvalidationCount());
-    List<TestAllTypes> messages = builder.build();
-    assertEquals(4, messages.size());
-    assertSame(messages, builder.build()); // expect same list
-
-    // Remove a message.
-    builder.remove(2);
-    assertEquals(1, mockParent.getInvalidationCount());
-    assertEquals(3, builder.getCount());
-    assertEquals(0, builder.getMessage(0).getOptionalInt32());
-    assertEquals(1, builder.getMessage(1).getOptionalInt32());
-    assertEquals(3, builder.getMessage(2).getOptionalInt32());
-
-    // Remove a builder.
-    builder.remove(0);
-    assertEquals(1, mockParent.getInvalidationCount());
-    assertEquals(2, builder.getCount());
-    assertEquals(1, builder.getMessage(0).getOptionalInt32());
-    assertEquals(3, builder.getMessage(1).getOptionalInt32());
-
-    // Test clear.
-    builder.clear();
-    assertEquals(1, mockParent.getInvalidationCount());
-    assertEquals(0, builder.getCount());
-    assertTrue(builder.isEmpty());
-  }
-
-  public void testLists() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    RepeatedFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder = newRepeatedFieldBuilder(mockParent);
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(1).build());
-    builder.addMessage(0,
-        TestAllTypes.newBuilder().setOptionalInt32(0).build());
-    assertEquals(0, builder.getMessage(0).getOptionalInt32());
-    assertEquals(1, builder.getMessage(1).getOptionalInt32());
-
-    // Use list of builders.
-    List<TestAllTypes.Builder> builders = builder.getBuilderList();
-    assertEquals(0, builders.get(0).getOptionalInt32());
-    assertEquals(1, builders.get(1).getOptionalInt32());
-    builders.get(0).setOptionalInt32(10);
-    builders.get(1).setOptionalInt32(11);
-
-    // Use list of protos
-    List<TestAllTypes> protos = builder.getMessageList();
-    assertEquals(10, protos.get(0).getOptionalInt32());
-    assertEquals(11, protos.get(1).getOptionalInt32());
-
-    // Add an item to the builders and verify it's updated in both
-    builder.addMessage(TestAllTypes.newBuilder().setOptionalInt32(12).build());
-    assertEquals(3, builders.size());
-    assertEquals(3, protos.size());
-  }
-
-  private void assertIsUnmodifiable(List<?> list) {
-    if (list == Collections.emptyList()) {
-      // OKAY -- Need to check this b/c EmptyList allows you to call clear.
-    } else {
-      try {
-        list.clear();
-        fail("List wasn't immutable");
-      } catch (UnsupportedOperationException e) {
-        // good
-      }
-    }
-  }
-
-  private RepeatedFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-      TestAllTypesOrBuilder>
-      newRepeatedFieldBuilder(GeneratedMessage.BuilderParent parent) {
-    return new RepeatedFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder>(Collections.<TestAllTypes>emptyList(), false,
-        parent, false);
-  }
-}
diff --git a/java/core/src/test/java/com/google/protobuf/SingleFieldBuilderTest.java b/java/core/src/test/java/com/google/protobuf/SingleFieldBuilderTest.java
deleted file mode 100644
index 58b80007..00000000
--- a/java/core/src/test/java/com/google/protobuf/SingleFieldBuilderTest.java
+++ /dev/null
@@ -1,155 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-package com.google.protobuf;
-
-import protobuf_unittest.UnittestProto.TestAllTypes;
-import protobuf_unittest.UnittestProto.TestAllTypesOrBuilder;
-
-import junit.framework.TestCase;
-
-/**
- * Tests for {@link SingleFieldBuilder}. This tests basic functionality.
- * More extensive testing is provided via other tests that exercise the
- * builder.
- *
- * @author jonp@google.com (Jon Perlow)
- */
-public class SingleFieldBuilderTest extends TestCase {
-
-  public void testBasicUseAndInvalidations() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder =
-        new SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-            TestAllTypesOrBuilder>(
-            TestAllTypes.getDefaultInstance(),
-            mockParent,
-            false);
-    assertSame(TestAllTypes.getDefaultInstance(), builder.getMessage());
-    assertEquals(TestAllTypes.getDefaultInstance(),
-        builder.getBuilder().buildPartial());
-    assertEquals(0, mockParent.getInvalidationCount());
-
-    builder.getBuilder().setOptionalInt32(10);
-    assertEquals(0, mockParent.getInvalidationCount());
-    TestAllTypes message = builder.build();
-    assertEquals(10, message.getOptionalInt32());
-
-    // Test that we receive invalidations now that build has been called.
-    assertEquals(0, mockParent.getInvalidationCount());
-    builder.getBuilder().setOptionalInt32(20);
-    assertEquals(1, mockParent.getInvalidationCount());
-
-    // Test that we don't keep getting invalidations on every change
-    builder.getBuilder().setOptionalInt32(30);
-    assertEquals(1, mockParent.getInvalidationCount());
-
-  }
-
-  public void testSetMessage() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder =
-        new SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-            TestAllTypesOrBuilder>(
-            TestAllTypes.getDefaultInstance(),
-            mockParent,
-            false);
-    builder.setMessage(TestAllTypes.newBuilder().setOptionalInt32(0).build());
-    assertEquals(0, builder.getMessage().getOptionalInt32());
-
-    // Update message using the builder
-    builder.getBuilder().setOptionalInt32(1);
-    assertEquals(0, mockParent.getInvalidationCount());
-    assertEquals(1, builder.getBuilder().getOptionalInt32());
-    assertEquals(1, builder.getMessage().getOptionalInt32());
-    builder.build();
-    builder.getBuilder().setOptionalInt32(2);
-    assertEquals(2, builder.getBuilder().getOptionalInt32());
-    assertEquals(2, builder.getMessage().getOptionalInt32());
-
-    // Make sure message stays cached
-    assertSame(builder.getMessage(), builder.getMessage());
-  }
-
-  public void testClear() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder =
-        new SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-            TestAllTypesOrBuilder>(
-            TestAllTypes.getDefaultInstance(),
-            mockParent,
-            false);
-    builder.setMessage(TestAllTypes.newBuilder().setOptionalInt32(0).build());
-    assertNotSame(TestAllTypes.getDefaultInstance(), builder.getMessage());
-    builder.clear();
-    assertSame(TestAllTypes.getDefaultInstance(), builder.getMessage());
-
-    builder.getBuilder().setOptionalInt32(1);
-    assertNotSame(TestAllTypes.getDefaultInstance(), builder.getMessage());
-    builder.clear();
-    assertSame(TestAllTypes.getDefaultInstance(), builder.getMessage());
-  }
-
-  public void testMerge() {
-    TestUtil.MockBuilderParent mockParent = new TestUtil.MockBuilderParent();
-    SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-        TestAllTypesOrBuilder> builder =
-        new SingleFieldBuilder<TestAllTypes, TestAllTypes.Builder,
-            TestAllTypesOrBuilder>(
-            TestAllTypes.getDefaultInstance(),
-            mockParent,
-            false);
-
-    // Merge into default field.
-    builder.mergeFrom(TestAllTypes.getDefaultInstance());
-    assertSame(TestAllTypes.getDefaultInstance(), builder.getMessage());
-
-    // Merge into non-default field on existing builder.
-    builder.getBuilder().setOptionalInt32(2);
-    builder.mergeFrom(TestAllTypes.newBuilder()
-        .setOptionalDouble(4.0)
-        .buildPartial());
-    assertEquals(2, builder.getMessage().getOptionalInt32());
-    assertEquals(4.0, builder.getMessage().getOptionalDouble());
-
-    // Merge into non-default field on existing message
-    builder.setMessage(TestAllTypes.newBuilder()
-        .setOptionalInt32(10)
-        .buildPartial());
-    builder.mergeFrom(TestAllTypes.newBuilder()
-        .setOptionalDouble(5.0)
-        .buildPartial());
-    assertEquals(10, builder.getMessage().getOptionalInt32());
-    assertEquals(5.0, builder.getMessage().getOptionalDouble());
-  }
-}