Integrated internal changes from Google

20 files changed, 433 insertions, 225 deletions

diff --git a/java/core/src/main/java/com/google/protobuf/AbstractParser.java b/java/core/src/main/java/com/google/protobuf/AbstractParser.java
index 66b0ee3b..7ff73ba4 100644
--- a/java/core/src/main/java/com/google/protobuf/AbstractParser.java
+++ b/java/core/src/main/java/com/google/protobuf/AbstractParser.java
@@ -232,7 +232,7 @@ public abstract class AbstractParser<MessageType extends MessageLite>
       }
       size = CodedInputStream.readRawVarint32(firstByte, input);
     } catch (IOException e) {
-      throw new InvalidProtocolBufferException(e.getMessage());
+      throw new InvalidProtocolBufferException(e);
     }
     InputStream limitedInput = new LimitedInputStream(input, size);
     return parsePartialFrom(limitedInput, extensionRegistry);
diff --git a/java/core/src/main/java/com/google/protobuf/ByteString.java b/java/core/src/main/java/com/google/protobuf/ByteString.java
index 5b24976d..99a31209 100644
--- a/java/core/src/main/java/com/google/protobuf/ByteString.java
+++ b/java/core/src/main/java/com/google/protobuf/ByteString.java
@@ -51,14 +51,12 @@ import java.util.List;
 import java.util.NoSuchElementException;
 
 /**
- * Immutable sequence of bytes.  Substring is supported by sharing the reference
- * to the immutable underlying bytes.  Concatenation is likewise supported
- * without copying (long strings) by building a tree of pieces in
- * {@link RopeByteString}.
- * <p>
- * Like {@link String}, the contents of a {@link ByteString} can never be
- * observed to change, not even in the presence of a data race or incorrect
- * API usage in the client code.
+ * Immutable sequence of bytes. Substring is supported by sharing the reference to the immutable
+ * underlying bytes. Concatenation is likewise supported without copying (long strings) by building
+ * a tree of pieces in {@link RopeByteString}.
+ *
+ * <p>Like {@link String}, the contents of a {@link ByteString} can never be observed to change, not
+ * even in the presence of a data race or incorrect API usage in the client code.
  *
  * @author crazybob@google.com Bob Lee
  * @author kenton@google.com Kenton Varda
@@ -565,7 +563,9 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
   // Create a balanced concatenation of the next "length" elements from the
   // iterable.
   private static ByteString balancedConcat(Iterator<ByteString> iterator, int length) {
-    assert length >= 1;
+    if (length < 1) {
+      throw new IllegalArgumentException(String.format("length (%s) must be >= 1", length));
+    }
     ByteString result;
     if (length == 1) {
       result = iterator.next();
diff --git a/java/core/src/main/java/com/google/protobuf/Descriptors.java b/java/core/src/main/java/com/google/protobuf/Descriptors.java
index cab7118a..38346f15 100644
--- a/java/core/src/main/java/com/google/protobuf/Descriptors.java
+++ b/java/core/src/main/java/com/google/protobuf/Descriptors.java
@@ -2123,7 +2123,7 @@ public final class Descriptors {
           // Can't happen, because addPackage() only fails when the name
           // conflicts with a non-package, but we have not yet added any
           // non-packages at this point.
-          assert false;
+          throw new AssertionError(e);
         }
       }
     }
diff --git a/java/core/src/main/java/com/google/protobuf/DynamicMessage.java b/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
index c54da67f..e6358c3b 100644
--- a/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
+++ b/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
@@ -297,7 +297,7 @@ public final class DynamicMessage extends AbstractMessage {
         } catch (InvalidProtocolBufferException e) {
           throw e.setUnfinishedMessage(builder.buildPartial());
         } catch (IOException e) {
-          throw new InvalidProtocolBufferException(e.getMessage())
+          throw new InvalidProtocolBufferException(e)
               .setUnfinishedMessage(builder.buildPartial());
         }
         return builder.buildPartial();
diff --git a/java/core/src/main/java/com/google/protobuf/ExtensionRegistry.java b/java/core/src/main/java/com/google/protobuf/ExtensionRegistry.java
index 1c2e7e6f..a22a74a0 100644
--- a/java/core/src/main/java/com/google/protobuf/ExtensionRegistry.java
+++ b/java/core/src/main/java/com/google/protobuf/ExtensionRegistry.java
@@ -32,7 +32,6 @@ package com.google.protobuf;
 
 import com.google.protobuf.Descriptors.Descriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
-
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
diff --git a/java/core/src/main/java/com/google/protobuf/ExtensionRegistryLite.java b/java/core/src/main/java/com/google/protobuf/ExtensionRegistryLite.java
index 5e4d7739..f3d48d3a 100644
--- a/java/core/src/main/java/com/google/protobuf/ExtensionRegistryLite.java
+++ b/java/core/src/main/java/com/google/protobuf/ExtensionRegistryLite.java
@@ -105,9 +105,9 @@ public class ExtensionRegistryLite {
 
   /**
    * Construct a new, empty instance.
-   * 
-   * <p>
-   * This may be an {@code ExtensionRegistry} if the full (non-Lite) proto libraries are available.
+   *
+   * <p>This may be an {@code ExtensionRegistry} if the full (non-Lite) proto libraries are
+   * available.
    */
   public static ExtensionRegistryLite newInstance() {
     return ExtensionRegistryFactory.create();
@@ -121,6 +121,7 @@ public class ExtensionRegistryLite {
     return ExtensionRegistryFactory.createEmpty();
   }
 
+
   /** Returns an unmodifiable view of the registry. */
   public ExtensionRegistryLite getUnmodifiable() {
     return new ExtensionRegistryLite(this);
diff --git a/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java b/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java
index 214971b1..f885b01e 100644
--- a/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java
+++ b/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java
@@ -39,7 +39,6 @@ import com.google.protobuf.Internal.IntList;
 import com.google.protobuf.Internal.LongList;
 import com.google.protobuf.Internal.ProtobufList;
 import com.google.protobuf.WireFormat.FieldType;
-
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.ObjectStreamException;
@@ -479,7 +478,6 @@ public abstract class GeneratedMessageLite<
         CodedInputStream input,
         ExtensionRegistryLite extensionRegistry,
         int tag) throws IOException {
-      int wireType = WireFormat.getTagWireType(tag);
       int fieldNumber = WireFormat.getTagFieldNumber(tag);
 
       // TODO(dweis): How much bytecode would be saved by not requiring the generated code to
@@ -487,6 +485,17 @@ public abstract class GeneratedMessageLite<
       GeneratedExtension<MessageType, ?> extension = extensionRegistry.findLiteExtensionByNumber(
           defaultInstance, fieldNumber);
 
+      return parseExtension(input, extensionRegistry, extension, tag, fieldNumber);
+    }
+
+    private boolean parseExtension(
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry,
+        GeneratedExtension<?, ?> extension,
+        int tag,
+        int fieldNumber)
+        throws IOException {
+      int wireType = WireFormat.getTagWireType(tag);
       boolean unknown = false;
       boolean packed = false;
       if (extension == null) {
@@ -508,7 +517,7 @@ public abstract class GeneratedMessageLite<
       if (unknown) {  // Unknown field or wrong wire type.  Skip.
         return parseUnknownField(tag, input);
       }
-
+      
       if (packed) {
         int length = input.readRawVarint32();
         int limit = input.pushLimit(length);
@@ -587,9 +596,147 @@ public abstract class GeneratedMessageLite<
                               extension.singularToFieldSetType(value));
         }
       }
-
       return true;
     }
+    
+    /**
+     * Parse an unknown field or an extension. For use by generated code only.
+     *
+     * <p>For use by generated code only.
+     *
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    protected <MessageType extends MessageLite> boolean parseUnknownFieldAsMessageSet(
+        MessageType defaultInstance,
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry,
+        int tag)
+        throws IOException {
+
+      if (tag == WireFormat.MESSAGE_SET_ITEM_TAG) {
+        mergeMessageSetExtensionFromCodedStream(defaultInstance, input, extensionRegistry);
+        return true;
+      }
+
+      // TODO(dweis): Do we really want to support non message set wire format in message sets?
+      // Full runtime does... So we do for now.
+      int wireType = WireFormat.getTagWireType(tag);
+      if (wireType == WireFormat.WIRETYPE_LENGTH_DELIMITED) {
+        return parseUnknownField(defaultInstance, input, extensionRegistry, tag);
+      } else {
+        // TODO(dweis): Should we throw on invalid input? Full runtime does not...
+        return input.skipField(tag);
+      }
+    }
+
+    /**
+     * Merges the message set from the input stream; requires message set wire format.
+     * 
+     * @param defaultInstance the default instance of the containing message we are parsing in
+     * @param input the stream to parse from
+     * @param extensionRegistry the registry to use when parsing
+     */
+    private <MessageType extends MessageLite> void mergeMessageSetExtensionFromCodedStream(
+        MessageType defaultInstance,
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry)
+        throws IOException {
+      // The wire format for MessageSet is:
+      //   message MessageSet {
+      //     repeated group Item = 1 {
+      //       required int32 typeId = 2;
+      //       required bytes message = 3;
+      //     }
+      //   }
+      // "typeId" is the extension's field number.  The extension can only be
+      // a message type, where "message" contains the encoded bytes of that
+      // message.
+      //
+      // In practice, we will probably never see a MessageSet item in which
+      // the message appears before the type ID, or where either field does not
+      // appear exactly once.  However, in theory such cases are valid, so we
+      // should be prepared to accept them.
+
+      int typeId = 0;
+      ByteString rawBytes = null; // If we encounter "message" before "typeId"
+      GeneratedExtension<?, ?> extension = null;
+
+      // Read bytes from input, if we get it's type first then parse it eagerly,
+      // otherwise we store the raw bytes in a local variable.
+      while (true) {
+        final int tag = input.readTag();
+        if (tag == 0) {
+          break;
+        }
+
+        if (tag == WireFormat.MESSAGE_SET_TYPE_ID_TAG) {
+          typeId = input.readUInt32();
+          if (typeId != 0) {
+            extension = extensionRegistry.findLiteExtensionByNumber(defaultInstance, typeId);
+          }
+
+        } else if (tag == WireFormat.MESSAGE_SET_MESSAGE_TAG) {
+          if (typeId != 0) {
+            if (extension != null) {
+              // We already know the type, so we can parse directly from the
+              // input with no copying.  Hooray!
+              eagerlyMergeMessageSetExtension(input, extension, extensionRegistry, typeId);
+              rawBytes = null;
+              continue;
+            }
+          }
+          // We haven't seen a type ID yet or we want parse message lazily.
+          rawBytes = input.readBytes();
+
+        } else { // Unknown tag. Skip it.
+          if (!input.skipField(tag)) {
+            break; // End of group
+          }
+        }
+      }
+      input.checkLastTagWas(WireFormat.MESSAGE_SET_ITEM_END_TAG);
+
+      // Process the raw bytes.
+      if (rawBytes != null && typeId != 0) { // Zero is not a valid type ID.
+        if (extension != null) { // We known the type
+          mergeMessageSetExtensionFromBytes(rawBytes, extensionRegistry, extension);
+        } else { // We don't know how to parse this. Ignore it.
+          if (rawBytes != null) {
+            mergeLengthDelimitedField(typeId, rawBytes);
+          }
+        }
+      }
+    }
+
+    private void eagerlyMergeMessageSetExtension(
+        CodedInputStream input,
+        GeneratedExtension<?, ?> extension,
+        ExtensionRegistryLite extensionRegistry,
+        int typeId)
+        throws IOException {
+      int fieldNumber = typeId;
+      int tag = WireFormat.makeTag(typeId, WireFormat.WIRETYPE_LENGTH_DELIMITED);
+      parseExtension(input, extensionRegistry, extension, tag, fieldNumber);
+    }
+
+    private void mergeMessageSetExtensionFromBytes(
+        ByteString rawBytes,
+        ExtensionRegistryLite extensionRegistry,
+        GeneratedExtension<?, ?> extension)
+        throws IOException {
+      MessageLite.Builder subBuilder = null;
+      MessageLite existingValue = (MessageLite) extensions.getField(extension.descriptor);
+      if (existingValue != null) {
+        subBuilder = existingValue.toBuilder();
+      }
+      if (subBuilder == null) {
+        subBuilder = extension.getMessageDefaultInstance().newBuilderForType();
+      }
+      rawBytes.newCodedInput().readMessage(subBuilder, extensionRegistry);
+      MessageLite value = subBuilder.build();
+
+      extensions.setField(extension.descriptor, extension.singularToFieldSetType(value));
+    }
 
     private void verifyExtensionContainingType(
         final GeneratedExtension<MessageType, ?> extension) {
@@ -807,14 +954,6 @@ public abstract class GeneratedMessageLite<
       return instance.getExtension(extension, index);
     }
 
-    // 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 dummy clone() implementation makes it go away.
-    @Override
-    public BuilderType clone() {
-      return super.clone();
-    }
-
     /** Set the value of an extension. */
     public final <Type> BuilderType setExtension(
         final ExtensionLite<MessageType, Type> extension,
diff --git a/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java b/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java
index 4cbbd296..2a5d8b50 100644
--- a/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java
+++ b/java/core/src/main/java/com/google/protobuf/GeneratedMessageV3.java
@@ -36,6 +36,16 @@ import com.google.protobuf.Descriptors.EnumValueDescriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
 import com.google.protobuf.Descriptors.FileDescriptor;
 import com.google.protobuf.Descriptors.OneofDescriptor;
+// In opensource protobuf, we have versioned this GeneratedMessageV3 class to GeneratedMessageV3V3 and
+// in the future may have GeneratedMessageV3V4 etc. This allows us to change some aspects of this
+// class without breaking binary compatibility with old generated code that still subclasses
+// the old GeneratedMessageV3 class. To allow these different GeneratedMessageV3V? classes to
+// interoperate (e.g., a GeneratedMessageV3V3 object has a message extension field whose class
+// type is GeneratedMessageV3V4), these classes still share a common parent class AbstarctMessage
+// and are using the same GeneratedMessage.GeneratedExtension class for extension definitions.
+// Since this class becomes GeneratedMessageV3V? in opensource, we have to add an import here
+// to be able to use GeneratedMessage.GeneratedExtension. The GeneratedExtension definition in
+// this file is also excluded from opensource to avoid conflict.
 import com.google.protobuf.GeneratedMessage.GeneratedExtension;
 
 import java.io.IOException;
@@ -1207,14 +1217,6 @@ public abstract class GeneratedMessageV3 extends AbstractMessage
       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();
@@ -1610,6 +1612,7 @@ public abstract class GeneratedMessageV3 extends AbstractMessage
     FieldDescriptor getDescriptor();
   }
 
+
   // =================================================================
 
   /** Calls Class.getMethod and throws a RuntimeException if it fails. */
@@ -1705,11 +1708,6 @@ public abstract class GeneratedMessageV3 extends AbstractMessage
       initialized = false;
     }
 
-    private boolean isMapFieldEnabled(FieldDescriptor field) {
-      boolean result = true;
-      return result;
-    }
-
     /**
      * Ensures the field accessors are initialized. This method is thread-safe.
      *
@@ -1733,7 +1731,7 @@ public abstract class GeneratedMessageV3 extends AbstractMessage
           }
           if (field.isRepeated()) {
             if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
-              if (field.isMapField() && isMapFieldEnabled(field)) {
+              if (field.isMapField()) {
                 fields[i] = new MapFieldAccessor(
                     field, camelCaseNames[i], messageClass, builderClass);
               } else {
diff --git a/java/core/src/main/java/com/google/protobuf/LazyFieldLite.java b/java/core/src/main/java/com/google/protobuf/LazyFieldLite.java
index 2febaace..4b0ba0fd 100644
--- a/java/core/src/main/java/com/google/protobuf/LazyFieldLite.java
+++ b/java/core/src/main/java/com/google/protobuf/LazyFieldLite.java
@@ -284,29 +284,8 @@ public class LazyFieldLite {
       return;
     }
 
-    // At this point we have two fully parsed messages. We can't merge directly from one to the
-    // other because only generated builder code contains methods to mergeFrom another parsed
-    // message. We have to serialize one instance and then merge the bytes into the other. This may
-    // drop extensions from one of the messages if one of the values had an extension set on it
-    // directly.
-    //
-    // To mitigate this we prefer serializing a message that has an extension registry, and
-    // therefore a chance that all extensions set on it are in that registry.
-    //
-    // NOTE: The check for other.extensionRegistry not being null must come first because at this
-    // point in time if other.extensionRegistry is not null then this.extensionRegistry will not be
-    // null either.
-    if (other.extensionRegistry != null) {
-      setValue(mergeValueAndBytes(this.value, other.toByteString(), other.extensionRegistry));
-      return;
-    } else if (this.extensionRegistry != null) {
-      setValue(mergeValueAndBytes(other.value, this.toByteString(), this.extensionRegistry));
-      return;
-    } else {
-      // All extensions from the other message will be dropped because we have no registry.
-      setValue(mergeValueAndBytes(this.value, other.toByteString(), EMPTY_REGISTRY));
-      return;
-    }
+    // At this point we have two fully parsed messages.
+    setValue(this.value.toBuilder().mergeFrom(other.value).build());
   }
   
   /**
diff --git a/java/core/src/main/java/com/google/protobuf/MapEntry.java b/java/core/src/main/java/com/google/protobuf/MapEntry.java
index 4f0351f4..179c3348 100644
--- a/java/core/src/main/java/com/google/protobuf/MapEntry.java
+++ b/java/core/src/main/java/com/google/protobuf/MapEntry.java
@@ -109,7 +109,7 @@ public final class MapEntry<K, V> extends AbstractMessage {
     } catch (InvalidProtocolBufferException e) {
       throw e.setUnfinishedMessage(this);
     } catch (IOException e) {
-      throw new InvalidProtocolBufferException(e.getMessage()).setUnfinishedMessage(this);
+      throw new InvalidProtocolBufferException(e).setUnfinishedMessage(this);
     }
   }
 
diff --git a/java/core/src/main/java/com/google/protobuf/MessageLiteToString.java b/java/core/src/main/java/com/google/protobuf/MessageLiteToString.java
index 43847651..23373ef4 100644
--- a/java/core/src/main/java/com/google/protobuf/MessageLiteToString.java
+++ b/java/core/src/main/java/com/google/protobuf/MessageLiteToString.java
@@ -95,7 +95,7 @@ final class MessageLiteToString {
         // Try to reflectively get the value and toString() the field as if it were repeated. This
         // only works if the method names have not be proguarded out or renamed.
         Method listMethod = nameToNoArgMethod.get("get" + suffix);
-        if (listMethod != null) {
+        if (listMethod != null && listMethod.getReturnType().equals(List.class)) {
           printField(
               buffer,
               indent,
@@ -115,7 +115,7 @@ final class MessageLiteToString {
         // Heuristic to skip bytes based accessors for string fields.
         continue;
       }
-      
+
       String camelCase = suffix.substring(0, 1).toLowerCase() + suffix.substring(1);
 
       // Try to reflectively get the value and toString() the field as if it were optional. This
diff --git a/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java b/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
index 6d33d3a8..49b3504f 100644
--- a/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
+++ b/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
@@ -1022,7 +1022,7 @@ public final class UnknownFieldSet implements MessageLite {
       } catch (InvalidProtocolBufferException e) {
         throw e.setUnfinishedMessage(builder.buildPartial());
       } catch (IOException e) {
-        throw new InvalidProtocolBufferException(e.getMessage())
+        throw new InvalidProtocolBufferException(e)
             .setUnfinishedMessage(builder.buildPartial());
       }
       return builder.buildPartial();
diff --git a/java/core/src/main/java/com/google/protobuf/UnknownFieldSetLite.java b/java/core/src/main/java/com/google/protobuf/UnknownFieldSetLite.java
index 9500f905..104f8007 100644
--- a/java/core/src/main/java/com/google/protobuf/UnknownFieldSetLite.java
+++ b/java/core/src/main/java/com/google/protobuf/UnknownFieldSetLite.java
@@ -176,6 +176,41 @@ public final class UnknownFieldSetLite {
   }
 
   /**
+   * Serializes the set and writes it to {@code output} using {@code MessageSet} wire format.
+   *
+   * <p>For use by generated code only.
+   */
+  public void writeAsMessageSetTo(CodedOutputStream output) throws IOException {
+    for (int i = 0; i < count; i++) {
+      int fieldNumber = WireFormat.getTagFieldNumber(tags[i]);
+      output.writeRawMessageSetExtension(fieldNumber, (ByteString) objects[i]);
+    }
+  }
+  
+  /**
+   * Get the number of bytes required to encode this field, including field
+   * number, using {@code MessageSet} wire format.
+   */
+  public int getSerializedSizeAsMessageSet() {
+    int size = memoizedSerializedSize;
+    if (size != -1) {
+      return size;
+    }
+    
+    size = 0;
+    for (int i = 0; i < count; i++) {
+      int tag = tags[i];
+      int fieldNumber = WireFormat.getTagFieldNumber(tag);
+      size += CodedOutputStream.computeRawMessageSetExtensionSize(
+          fieldNumber, (ByteString) objects[i]);
+    }
+    
+    memoizedSerializedSize = size;
+    
+    return size;
+  }
+
+  /**
    * Get the number of bytes required to encode this set.
    *
    * <p>For use by generated code only.
@@ -268,7 +303,8 @@ public final class UnknownFieldSetLite {
     }
   }
 
-  private void storeField(int tag, Object value) {
+  // Package private for unsafe experimental runtime.
+  void storeField(int tag, Object value) {
     ensureCapacity();
     
     tags[count] = tag;
diff --git a/java/core/src/test/java/com/google/protobuf/LazyFieldLiteTest.java b/java/core/src/test/java/com/google/protobuf/LazyFieldLiteTest.java
index efdfdfbe..813fe6bc 100644
--- a/java/core/src/test/java/com/google/protobuf/LazyFieldLiteTest.java
+++ b/java/core/src/test/java/com/google/protobuf/LazyFieldLiteTest.java
@@ -31,7 +31,6 @@
 package com.google.protobuf;
 
 import static protobuf_unittest.UnittestProto.optionalInt32Extension;
-import static protobuf_unittest.UnittestProto.optionalInt64Extension;
 
 import protobuf_unittest.UnittestProto.TestAllExtensions;
 import protobuf_unittest.UnittestProto.TestAllTypes;
@@ -219,29 +218,6 @@ public class LazyFieldLiteTest extends TestCase {
     assertEquals(messageWithExtensions, field.getValue(TestAllExtensions.getDefaultInstance()));
   }
 
-  public void testMergeMightLoseExtensions() throws Exception {
-    // Test that we don't know about the extensions when parsing.
-    TestAllExtensions message1 =
-        TestAllExtensions.newBuilder().setExtension(optionalInt32Extension, 1).build();
-    TestAllExtensions message2 =
-        TestAllExtensions.newBuilder().setExtension(optionalInt64Extension, 2L).build();
-
-    LazyFieldLite field = LazyFieldLite.fromValue(message1);
-    field.merge(LazyFieldLite.fromValue(message2));
-
-    // We lose the extensions from message 2 because we have to serialize it and then parse it
-    // again, using the empty registry this time.
-    TestAllExtensions value =
-        (TestAllExtensions) field.getValue(TestAllExtensions.getDefaultInstance());
-    assertTrue(value.hasExtension(optionalInt32Extension));
-    assertEquals(Integer.valueOf(1), value.getExtension(optionalInt32Extension));
-    assertFalse(value.hasExtension(optionalInt64Extension));
-
-    // The field is still there, it is just unknown.
-    assertTrue(value.getUnknownFields()
-        .hasField(optionalInt64Extension.getDescriptor().getNumber()));
-  }
-
 
   // Help methods.
 
diff --git a/java/core/src/test/java/com/google/protobuf/LazyMessageLiteTest.java b/java/core/src/test/java/com/google/protobuf/LazyMessageLiteTest.java
index c8ca9b6a..968ca206 100644
--- a/java/core/src/test/java/com/google/protobuf/LazyMessageLiteTest.java
+++ b/java/core/src/test/java/com/google/protobuf/LazyMessageLiteTest.java
@@ -101,6 +101,19 @@ public class LazyMessageLiteTest extends TestCase {
     assertEquals(119, outer.getRepeatedInner(0).getNum());
     assertEquals(122, outer.getRepeatedInner(1).getNum());
   }
+  
+  public void testRepeatedMutability() throws Exception {
+    LazyMessageLite outer = LazyMessageLite.newBuilder()
+        .addRepeatedInner(LazyInnerMessageLite.newBuilder().setNum(119))
+        .addRepeatedInner(LazyInnerMessageLite.newBuilder().setNum(122))
+        .build();
+    
+    outer = LazyMessageLite.parseFrom(outer.toByteArray());
+    try {
+      outer.getRepeatedInnerList().set(1, null);
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+  }
 
   public void testAddAll() {
     ArrayList<LazyInnerMessageLite> inners = new ArrayList<LazyInnerMessageLite>();
diff --git a/java/core/src/test/java/com/google/protobuf/LiteTest.java b/java/core/src/test/java/com/google/protobuf/LiteTest.java
index 254beba1..538432f7 100644
--- a/java/core/src/test/java/com/google/protobuf/LiteTest.java
+++ b/java/core/src/test/java/com/google/protobuf/LiteTest.java
@@ -45,6 +45,7 @@ import com.google.protobuf.UnittestLite.TestAllTypesLite.OneofFieldCase;
 import com.google.protobuf.UnittestLite.TestAllTypesLite.OptionalGroup;
 import com.google.protobuf.UnittestLite.TestAllTypesLite.RepeatedGroup;
 import com.google.protobuf.UnittestLite.TestAllTypesLiteOrBuilder;
+import com.google.protobuf.UnittestLite.TestHugeFieldNumbersLite;
 import com.google.protobuf.UnittestLite.TestNestedExtensionLite;
 import protobuf_unittest.lite_equals_and_hash.LiteEqualsAndHash.Bar;
 import protobuf_unittest.lite_equals_and_hash.LiteEqualsAndHash.BarPrime;
@@ -1424,6 +1425,12 @@ public class LiteTest extends TestCase {
     assertToStringEquals("", TestAllTypesLite.getDefaultInstance());
   }
 
+  public void testToStringScalarFieldsSuffixedWithList() throws Exception {
+    assertToStringEquals("deceptively_named_list: 7", TestAllTypesLite.newBuilder()
+        .setDeceptivelyNamedList(7)
+        .build());
+  }
+
   public void testToStringPrimitives() throws Exception {
     TestAllTypesLite proto = TestAllTypesLite.newBuilder()
         .setOptionalInt32(1)
@@ -2235,6 +2242,25 @@ public class LiteTest extends TestCase {
     assertFalse(other.equals(mine));
   }
 
+  public void testHugeFieldNumbers() throws InvalidProtocolBufferException {
+    TestHugeFieldNumbersLite message =
+        TestHugeFieldNumbersLite.newBuilder()
+            .setOptionalInt32(1)
+            .addRepeatedInt32(2)
+            .setOptionalEnum(ForeignEnumLite.FOREIGN_LITE_FOO)
+            .setOptionalString("xyz")
+            .setOptionalMessage(ForeignMessageLite.newBuilder().setC(3).build())
+            .build();
+
+    TestHugeFieldNumbersLite parsedMessage =
+        TestHugeFieldNumbersLite.parseFrom(message.toByteArray());
+    assertEquals(1, parsedMessage.getOptionalInt32());
+    assertEquals(2, parsedMessage.getRepeatedInt32(0));
+    assertEquals(ForeignEnumLite.FOREIGN_LITE_FOO, parsedMessage.getOptionalEnum());
+    assertEquals("xyz", parsedMessage.getOptionalString());
+    assertEquals(3, parsedMessage.getOptionalMessage().getC());
+  }
+
   private void assertEqualsAndHashCodeAreFalse(Object o1, Object o2) {
     assertFalse(o1.equals(o2));
     assertFalse(o1.hashCode() == o2.hashCode());
diff --git a/java/core/src/test/java/com/google/protobuf/MapForProto2LiteTest.java b/java/core/src/test/java/com/google/protobuf/MapForProto2LiteTest.java
index 8b64fa27..0a14f584 100644
--- a/java/core/src/test/java/com/google/protobuf/MapForProto2LiteTest.java
+++ b/java/core/src/test/java/com/google/protobuf/MapForProto2LiteTest.java
@@ -501,7 +501,6 @@ public final class MapForProto2LiteTest extends TestCase {
     assertEquals(54321, messageWithUnknownEnums.getInt32ToInt32Field().get(2).intValue());
   }
 
-
   public void testIterationOrder() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
     setMapValues(builder);
diff --git a/java/core/src/test/java/com/google/protobuf/MapForProto2Test.java b/java/core/src/test/java/com/google/protobuf/MapForProto2Test.java
index 76bd7bd9..cfe4c453 100644
--- a/java/core/src/test/java/com/google/protobuf/MapForProto2Test.java
+++ b/java/core/src/test/java/com/google/protobuf/MapForProto2Test.java
@@ -58,26 +58,26 @@ public class MapForProto2Test extends TestCase {
     builder.getMutableInt32ToInt32Field().put(1, 11);
     builder.getMutableInt32ToInt32Field().put(2, 22);
     builder.getMutableInt32ToInt32Field().put(3, 33);
-
+  //
     builder.getMutableInt32ToStringField().put(1, "11");
     builder.getMutableInt32ToStringField().put(2, "22");
     builder.getMutableInt32ToStringField().put(3, "33");
-
+  //
     builder.getMutableInt32ToBytesField().put(1, TestUtil.toBytes("11"));
     builder.getMutableInt32ToBytesField().put(2, TestUtil.toBytes("22"));
     builder.getMutableInt32ToBytesField().put(3, TestUtil.toBytes("33"));
-
+  //
     builder.getMutableInt32ToEnumField().put(1, TestMap.EnumValue.FOO);
     builder.getMutableInt32ToEnumField().put(2, TestMap.EnumValue.BAR);
     builder.getMutableInt32ToEnumField().put(3, TestMap.EnumValue.BAZ);
-
+  //
     builder.getMutableInt32ToMessageField().put(
         1, MessageValue.newBuilder().setValue(11).build());
     builder.getMutableInt32ToMessageField().put(
         2, MessageValue.newBuilder().setValue(22).build());
     builder.getMutableInt32ToMessageField().put(
         3, MessageValue.newBuilder().setValue(33).build());
-
+  //
     builder.getMutableStringToInt32Field().put("1", 11);
     builder.getMutableStringToInt32Field().put("2", 22);
     builder.getMutableStringToInt32Field().put("3", 33);
@@ -120,6 +120,7 @@ public class MapForProto2Test extends TestCase {
     setMapValuesUsingAccessors(usingAccessorsBuilder);
     TestMap usingAccessors = usingAccessorsBuilder.build();
     assertMapValuesSet(usingAccessors);
+
     assertEquals(usingAccessors, usingMutableMap);
   }
 
@@ -169,25 +170,25 @@ public class MapForProto2Test extends TestCase {
     builder.getMutableInt32ToInt32Field().put(1, 111);
     builder.getMutableInt32ToInt32Field().remove(2);
     builder.getMutableInt32ToInt32Field().put(4, 44);
-
+  //
     builder.getMutableInt32ToStringField().put(1, "111");
     builder.getMutableInt32ToStringField().remove(2);
     builder.getMutableInt32ToStringField().put(4, "44");
-
+  //
     builder.getMutableInt32ToBytesField().put(1, TestUtil.toBytes("111"));
     builder.getMutableInt32ToBytesField().remove(2);
     builder.getMutableInt32ToBytesField().put(4, TestUtil.toBytes("44"));
-
+  //
     builder.getMutableInt32ToEnumField().put(1, TestMap.EnumValue.BAR);
     builder.getMutableInt32ToEnumField().remove(2);
     builder.getMutableInt32ToEnumField().put(4, TestMap.EnumValue.QUX);
-
+  //
     builder.getMutableInt32ToMessageField().put(
         1, MessageValue.newBuilder().setValue(111).build());
     builder.getMutableInt32ToMessageField().remove(2);
     builder.getMutableInt32ToMessageField().put(
         4, MessageValue.newBuilder().setValue(44).build());
-
+  //
     builder.getMutableStringToInt32Field().put("1", 111);
     builder.getMutableStringToInt32Field().remove("2");
     builder.getMutableStringToInt32Field().put("4", 44);
@@ -230,8 +231,9 @@ public class MapForProto2Test extends TestCase {
     setMapValuesUsingAccessors(usingAccessorsBuilder);
     TestMap usingAccessors = usingAccessorsBuilder.build();
     assertMapValuesSet(usingAccessors);
-    assertEquals(usingAccessors, usingMutableMap);
 
+    assertEquals(usingAccessors, usingMutableMap);
+    //
     usingMutableMapBuilder = usingMutableMap.toBuilder();
     updateMapValuesUsingMutableMap(usingMutableMapBuilder);
     usingMutableMap = usingMutableMapBuilder.build();
@@ -335,7 +337,7 @@ public class MapForProto2Test extends TestCase {
     assertEquals(newMap(1, 2), builder.getInt32ToInt32Field());
     builder.getMutableInt32ToInt32Field().put(2, 3);
     assertEquals(newMap(1, 2, 2, 3), builder.getInt32ToInt32Field());
-
+ //
     Map<Integer, TestMap.EnumValue> enumMap = builder.getMutableInt32ToEnumField();
     enumMap.put(1, TestMap.EnumValue.BAR);
     assertEquals(newMap(1, TestMap.EnumValue.BAR), builder.build().getInt32ToEnumField());
@@ -350,7 +352,7 @@ public class MapForProto2Test extends TestCase {
     assertEquals(
         newMap(1, TestMap.EnumValue.BAR, 2, TestMap.EnumValue.FOO),
         builder.getInt32ToEnumField());
-
+  //
     Map<Integer, String> stringMap = builder.getMutableInt32ToStringField();
     stringMap.put(1, "1");
     assertEquals(newMap(1, "1"), builder.build().getInt32ToStringField());
@@ -365,7 +367,7 @@ public class MapForProto2Test extends TestCase {
     assertEquals(
         newMap(1, "1", 2, "2"),
         builder.getInt32ToStringField());
-
+  //
     Map<Integer, TestMap.MessageValue> messageMap = builder.getMutableInt32ToMessageField();
     messageMap.put(1, TestMap.MessageValue.getDefaultInstance());
     assertEquals(newMap(1, TestMap.MessageValue.getDefaultInstance()),
@@ -384,7 +386,7 @@ public class MapForProto2Test extends TestCase {
             2, TestMap.MessageValue.getDefaultInstance()),
         builder.getInt32ToMessageField());
   }
-
+  //
   public void testMutableMapLifecycle_collections() {
     TestMap.Builder builder = TestMap.newBuilder();
     Map<Integer, Integer> intMap = builder.getMutableInt32ToInt32Field();
@@ -431,18 +433,19 @@ public class MapForProto2Test extends TestCase {
     assertEquals(newMap(1, 2), builder.build().getInt32ToInt32Field());
   }
 
+
   public void testGettersAndSetters() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
     TestMap message = builder.build();
     assertMapValuesCleared(message);
 
     builder = message.toBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     message = builder.build();
     assertMapValuesSet(message);
 
     builder = message.toBuilder();
-    updateMapValuesUsingMutableMap(builder);
+    updateMapValuesUsingAccessors(builder);
     message = builder.build();
     assertMapValuesUpdated(message);
 
@@ -455,7 +458,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testPutAll() throws Exception {
     TestMap.Builder sourceBuilder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(sourceBuilder);
+    setMapValuesUsingAccessors(sourceBuilder);
     TestMap source = sourceBuilder.build();
     assertMapValuesSet(source);
 
@@ -507,14 +510,14 @@ public class MapForProto2Test extends TestCase {
 
   public void testSerializeAndParse() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
     assertEquals(message.getSerializedSize(), message.toByteString().size());
     message = TestMap.parser().parseFrom(message.toByteString());
     assertMapValuesSet(message);
 
     builder = message.toBuilder();
-    updateMapValuesUsingMutableMap(builder);
+    updateMapValuesUsingAccessors(builder);
     message = builder.build();
     assertEquals(message.getSerializedSize(), message.toByteString().size());
     message = TestMap.parser().parseFrom(message.toByteString());
@@ -579,7 +582,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testMergeFrom() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     TestMap.Builder other = TestMap.newBuilder();
@@ -594,22 +597,22 @@ public class MapForProto2Test extends TestCase {
     // We can't control the order of elements in a HashMap. The best we can do
     // here is to add elements in different order.
     TestMap.Builder b1 = TestMap.newBuilder();
-    b1.getMutableInt32ToInt32Field().put(1, 2);
-    b1.getMutableInt32ToInt32Field().put(3, 4);
-    b1.getMutableInt32ToInt32Field().put(5, 6);
+    b1.putInt32ToInt32Field(1, 2);
+    b1.putInt32ToInt32Field(3, 4);
+    b1.putInt32ToInt32Field(5, 6);
     TestMap m1 = b1.build();
 
     TestMap.Builder b2 = TestMap.newBuilder();
-    b2.getMutableInt32ToInt32Field().put(5, 6);
-    b2.getMutableInt32ToInt32Field().put(1, 2);
-    b2.getMutableInt32ToInt32Field().put(3, 4);
+    b2.putInt32ToInt32Field(5, 6);
+    b2.putInt32ToInt32Field(1, 2);
+    b2.putInt32ToInt32Field(3, 4);
     TestMap m2 = b2.build();
 
     assertEquals(m1, m2);
     assertEquals(m1.hashCode(), m2.hashCode());
 
     // Make sure we did compare map fields.
-    b2.getMutableInt32ToInt32Field().put(1, 0);
+    b2.putInt32ToInt32Field(1, 0);
     m2 = b2.build();
     assertFalse(m1.equals(m2));
     // Don't check m1.hashCode() != m2.hashCode() because it's not guaranteed
@@ -684,13 +687,11 @@ public class MapForProto2Test extends TestCase {
 
   public void testReflectionApi() throws Exception {
     // In reflection API, map fields are just repeated message fields.
-    TestMap.Builder builder = TestMap.newBuilder();
-    builder.getMutableInt32ToInt32Field().put(1, 2);
-    builder.getMutableInt32ToInt32Field().put(3, 4);
-    builder.getMutableInt32ToMessageField().put(
-        11, MessageValue.newBuilder().setValue(22).build());
-    builder.getMutableInt32ToMessageField().put(
-        33, MessageValue.newBuilder().setValue(44).build());
+    TestMap.Builder builder = TestMap.newBuilder()
+        .putInt32ToInt32Field(1, 2)
+        .putInt32ToInt32Field(3, 4)
+        .putInt32ToMessageField(11, MessageValue.newBuilder().setValue(22).build())
+        .putInt32ToMessageField(33, MessageValue.newBuilder().setValue(44).build());
     TestMap message = builder.build();
 
     // Test getField(), getRepeatedFieldCount(), getRepeatedField().
@@ -760,7 +761,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testTextFormat() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     String textData = TextFormat.printToString(message);
@@ -774,7 +775,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testDynamicMessage() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     Message dynamicDefaultInstance =
@@ -819,10 +820,9 @@ public class MapForProto2Test extends TestCase {
   }
 
   public void testUnknownEnumValues() throws Exception {
-    TestUnknownEnumValue.Builder builder =
-        TestUnknownEnumValue.newBuilder();
-    builder.getMutableInt32ToInt32Field().put(1, 1);
-    builder.getMutableInt32ToInt32Field().put(2, 54321);
+    TestUnknownEnumValue.Builder builder = TestUnknownEnumValue.newBuilder()
+        .putInt32ToInt32Field(1, 1)
+        .putInt32ToInt32Field(2, 54321);
     ByteString data = builder.build().toByteString();
 
     TestMap message = TestMap.parseFrom(data);
@@ -841,26 +841,21 @@ public class MapForProto2Test extends TestCase {
     assertEquals(54321, messageWithUnknownEnums.getInt32ToInt32Field().get(2).intValue());
   }
 
-
   public void testRequiredMessage() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    builder.getMutableRequiredMessageMap().put(0,
-        MessageWithRequiredFields.newBuilder().buildPartial());
+    builder.putRequiredMessageMap(0, MessageWithRequiredFields.newBuilder().buildPartial());
     TestMap message = builder.buildPartial();
     assertFalse(message.isInitialized());
 
-    builder.getMutableRequiredMessageMap().put(0,
-        MessageWithRequiredFields.newBuilder().setValue(1).build());
+    builder.putRequiredMessageMap(0, MessageWithRequiredFields.newBuilder().setValue(1).build());
     message = builder.build();
     assertTrue(message.isInitialized());
   }
 
   public void testRecursiveMap() throws Exception {
     TestRecursiveMap.Builder builder = TestRecursiveMap.newBuilder();
-    builder.getMutableRecursiveMapField().put(
-        1, TestRecursiveMap.newBuilder().setValue(2).build());
-    builder.getMutableRecursiveMapField().put(
-        3, TestRecursiveMap.newBuilder().setValue(4).build());
+    builder.putRecursiveMapField(1, TestRecursiveMap.newBuilder().setValue(2).build());
+    builder.putRecursiveMapField(3, TestRecursiveMap.newBuilder().setValue(4).build());
     ByteString data = builder.build().toByteString();
 
     TestRecursiveMap message = TestRecursiveMap.parseFrom(data);
@@ -870,7 +865,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testIterationOrder() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     assertEquals(Arrays.asList("1", "2", "3"),
@@ -879,7 +874,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testContains() {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     assertMapContainsSetValues(builder);
     assertMapContainsSetValues(builder.build());
   }
@@ -920,7 +915,7 @@ public class MapForProto2Test extends TestCase {
     TestMap.Builder builder = TestMap.newBuilder();
     assertMapCounts(0, builder);
 
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     assertMapCounts(3, builder);
 
     TestMap message = builder.build();
@@ -1091,7 +1086,7 @@ public class MapForProto2Test extends TestCase {
 
   public void testRemove() {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     assertEquals(11, builder.getInt32ToInt32FieldOrThrow(1));
     for (int times = 0; times < 2; times++) {
       builder.removeInt32ToInt32Field(1);
@@ -1137,7 +1132,7 @@ public class MapForProto2Test extends TestCase {
 
     map_test.Message1.Builder builder =
         map_test.Message1.newBuilder();
-    builder.getMutableMapField().put("key", true);
+    builder.putMapField("key", true);
     map_test.Message1 message = builder.build();
     Message mapEntry = (Message) message.getRepeatedField(
         message.getDescriptorForType().findFieldByName("map_field"), 0);
diff --git a/java/core/src/test/java/com/google/protobuf/MapTest.java b/java/core/src/test/java/com/google/protobuf/MapTest.java
index 035a8335..81e951cc 100644
--- a/java/core/src/test/java/com/google/protobuf/MapTest.java
+++ b/java/core/src/test/java/com/google/protobuf/MapTest.java
@@ -60,26 +60,26 @@ public class MapTest extends TestCase {
     builder.getMutableInt32ToInt32Field().put(1, 11);
     builder.getMutableInt32ToInt32Field().put(2, 22);
     builder.getMutableInt32ToInt32Field().put(3, 33);
-
+  //
     builder.getMutableInt32ToStringField().put(1, "11");
     builder.getMutableInt32ToStringField().put(2, "22");
     builder.getMutableInt32ToStringField().put(3, "33");
-
+  //
     builder.getMutableInt32ToBytesField().put(1, TestUtil.toBytes("11"));
     builder.getMutableInt32ToBytesField().put(2, TestUtil.toBytes("22"));
     builder.getMutableInt32ToBytesField().put(3, TestUtil.toBytes("33"));
-
+  //
     builder.getMutableInt32ToEnumField().put(1, TestMap.EnumValue.FOO);
     builder.getMutableInt32ToEnumField().put(2, TestMap.EnumValue.BAR);
     builder.getMutableInt32ToEnumField().put(3, TestMap.EnumValue.BAZ);
-
+  //
     builder.getMutableInt32ToMessageField().put(
         1, MessageValue.newBuilder().setValue(11).build());
     builder.getMutableInt32ToMessageField().put(
         2, MessageValue.newBuilder().setValue(22).build());
     builder.getMutableInt32ToMessageField().put(
         3, MessageValue.newBuilder().setValue(33).build());
-
+  //
     builder.getMutableStringToInt32Field().put("1", 11);
     builder.getMutableStringToInt32Field().put("2", 22);
     builder.getMutableStringToInt32Field().put("3", 33);
@@ -122,6 +122,7 @@ public class MapTest extends TestCase {
     setMapValuesUsingAccessors(usingAccessorsBuilder);
     TestMap usingAccessors = usingAccessorsBuilder.build();
     assertMapValuesSet(usingAccessors);
+
     assertEquals(usingAccessors, usingMutableMap);
   }
 
@@ -171,25 +172,25 @@ public class MapTest extends TestCase {
     builder.getMutableInt32ToInt32Field().put(1, 111);
     builder.getMutableInt32ToInt32Field().remove(2);
     builder.getMutableInt32ToInt32Field().put(4, 44);
-
+  //
     builder.getMutableInt32ToStringField().put(1, "111");
     builder.getMutableInt32ToStringField().remove(2);
     builder.getMutableInt32ToStringField().put(4, "44");
-
+  //
     builder.getMutableInt32ToBytesField().put(1, TestUtil.toBytes("111"));
     builder.getMutableInt32ToBytesField().remove(2);
     builder.getMutableInt32ToBytesField().put(4, TestUtil.toBytes("44"));
-
+  //
     builder.getMutableInt32ToEnumField().put(1, TestMap.EnumValue.BAR);
     builder.getMutableInt32ToEnumField().remove(2);
     builder.getMutableInt32ToEnumField().put(4, TestMap.EnumValue.QUX);
-
+  //
     builder.getMutableInt32ToMessageField().put(
         1, MessageValue.newBuilder().setValue(111).build());
     builder.getMutableInt32ToMessageField().remove(2);
     builder.getMutableInt32ToMessageField().put(
         4, MessageValue.newBuilder().setValue(44).build());
-
+  //
     builder.getMutableStringToInt32Field().put("1", 111);
     builder.getMutableStringToInt32Field().remove("2");
     builder.getMutableStringToInt32Field().put("4", 44);
@@ -232,8 +233,9 @@ public class MapTest extends TestCase {
     setMapValuesUsingAccessors(usingAccessorsBuilder);
     TestMap usingAccessors = usingAccessorsBuilder.build();
     assertMapValuesSet(usingAccessors);
-    assertEquals(usingAccessors, usingMutableMap);
 
+    assertEquals(usingAccessors, usingMutableMap);
+    //
     usingMutableMapBuilder = usingMutableMap.toBuilder();
     updateMapValuesUsingMutableMap(usingMutableMapBuilder);
     usingMutableMap = usingMutableMapBuilder.build();
@@ -337,7 +339,7 @@ public class MapTest extends TestCase {
     assertEquals(newMap(1, 2), builder.getInt32ToInt32Field());
     builder.getMutableInt32ToInt32Field().put(2, 3);
     assertEquals(newMap(1, 2, 2, 3), builder.getInt32ToInt32Field());
-
+  //
     Map<Integer, TestMap.EnumValue> enumMap = builder.getMutableInt32ToEnumField();
     enumMap.put(1, TestMap.EnumValue.BAR);
     assertEquals(newMap(1, TestMap.EnumValue.BAR), builder.build().getInt32ToEnumField());
@@ -352,7 +354,7 @@ public class MapTest extends TestCase {
     assertEquals(
         newMap(1, TestMap.EnumValue.BAR, 2, TestMap.EnumValue.FOO),
         builder.getInt32ToEnumField());
-
+  //
     Map<Integer, String> stringMap = builder.getMutableInt32ToStringField();
     stringMap.put(1, "1");
     assertEquals(newMap(1, "1"), builder.build().getInt32ToStringField());
@@ -363,11 +365,11 @@ public class MapTest extends TestCase {
       // expected
     }
     assertEquals(newMap(1, "1"), builder.getInt32ToStringField());
-    builder.getMutableInt32ToStringField().put(2, "2");
+    builder.putInt32ToStringField(2, "2");
     assertEquals(
         newMap(1, "1", 2, "2"),
         builder.getInt32ToStringField());
-
+  //
     Map<Integer, TestMap.MessageValue> messageMap = builder.getMutableInt32ToMessageField();
     messageMap.put(1, TestMap.MessageValue.getDefaultInstance());
     assertEquals(newMap(1, TestMap.MessageValue.getDefaultInstance()),
@@ -380,13 +382,13 @@ public class MapTest extends TestCase {
     }
     assertEquals(newMap(1, TestMap.MessageValue.getDefaultInstance()),
         builder.getInt32ToMessageField());
-    builder.getMutableInt32ToMessageField().put(2, TestMap.MessageValue.getDefaultInstance());
+    builder.putInt32ToMessageField(2, TestMap.MessageValue.getDefaultInstance());
     assertEquals(
         newMap(1, TestMap.MessageValue.getDefaultInstance(),
             2, TestMap.MessageValue.getDefaultInstance()),
         builder.getInt32ToMessageField());
   }
-
+  //
   public void testMutableMapLifecycle_collections() {
     TestMap.Builder builder = TestMap.newBuilder();
     Map<Integer, Integer> intMap = builder.getMutableInt32ToInt32Field();
@@ -433,18 +435,19 @@ public class MapTest extends TestCase {
     assertEquals(newMap(1, 2), builder.build().getInt32ToInt32Field());
   }
 
+
   public void testGettersAndSetters() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
     TestMap message = builder.build();
     assertMapValuesCleared(message);
 
     builder = message.toBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     message = builder.build();
     assertMapValuesSet(message);
 
     builder = message.toBuilder();
-    updateMapValuesUsingMutableMap(builder);
+    updateMapValuesUsingAccessors(builder);
     message = builder.build();
     assertMapValuesUpdated(message);
 
@@ -457,7 +460,7 @@ public class MapTest extends TestCase {
 
   public void testPutAll() throws Exception {
     TestMap.Builder sourceBuilder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(sourceBuilder);
+    setMapValuesUsingAccessors(sourceBuilder);
     TestMap source = sourceBuilder.build();
     assertMapValuesSet(source);
 
@@ -467,15 +470,16 @@ public class MapTest extends TestCase {
   }
 
   public void testPutAllForUnknownEnumValues() throws Exception {
-    TestMap.Builder sourceBuilder = TestMap.newBuilder();
-    sourceBuilder.getMutableInt32ToEnumFieldValue().put(0, 0);
-    sourceBuilder.getMutableInt32ToEnumFieldValue().put(1, 1);
-    sourceBuilder.getMutableInt32ToEnumFieldValue().put(2, 1000);  // unknown value.
-    TestMap source = sourceBuilder.build();
+    TestMap source = TestMap.newBuilder()
+        .putAllInt32ToEnumFieldValue(newMap(
+            0, 0,
+            1, 1,
+            2, 1000)) // unknown value.
+        .build();
 
-    TestMap.Builder destinationBuilder = TestMap.newBuilder();
-    destinationBuilder.putAllInt32ToEnumFieldValue(source.getInt32ToEnumFieldValue());
-    TestMap destination = destinationBuilder.build();
+    TestMap destination = TestMap.newBuilder()
+        .putAllInt32ToEnumFieldValue(source.getInt32ToEnumFieldValue())
+        .build();
 
     assertEquals(0, destination.getInt32ToEnumFieldValue().get(0).intValue());
     assertEquals(1, destination.getInt32ToEnumFieldValue().get(1).intValue());
@@ -542,14 +546,14 @@ public class MapTest extends TestCase {
 
   public void testSerializeAndParse() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
     assertEquals(message.getSerializedSize(), message.toByteString().size());
     message = TestMap.parser().parseFrom(message.toByteString());
     assertMapValuesSet(message);
 
     builder = message.toBuilder();
-    updateMapValuesUsingMutableMap(builder);
+    updateMapValuesUsingAccessors(builder);
     message = builder.build();
     assertEquals(message.getSerializedSize(), message.toByteString().size());
     message = TestMap.parser().parseFrom(message.toByteString());
@@ -614,7 +618,7 @@ public class MapTest extends TestCase {
 
   public void testMergeFrom() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     TestMap.Builder other = TestMap.newBuilder();
@@ -628,23 +632,23 @@ public class MapTest extends TestCase {
 
     // We can't control the order of elements in a HashMap. The best we can do
     // here is to add elements in different order.
-    TestMap.Builder b1 = TestMap.newBuilder();
-    b1.getMutableInt32ToInt32Field().put(1, 2);
-    b1.getMutableInt32ToInt32Field().put(3, 4);
-    b1.getMutableInt32ToInt32Field().put(5, 6);
+    TestMap.Builder b1 = TestMap.newBuilder()
+        .putInt32ToInt32Field(1, 2)
+        .putInt32ToInt32Field(3, 4)
+        .putInt32ToInt32Field(5, 6);
     TestMap m1 = b1.build();
 
-    TestMap.Builder b2 = TestMap.newBuilder();
-    b2.getMutableInt32ToInt32Field().put(5, 6);
-    b2.getMutableInt32ToInt32Field().put(1, 2);
-    b2.getMutableInt32ToInt32Field().put(3, 4);
+    TestMap.Builder b2 = TestMap.newBuilder()
+        .putInt32ToInt32Field(5, 6)
+        .putInt32ToInt32Field(1, 2)
+        .putInt32ToInt32Field(3, 4);
     TestMap m2 = b2.build();
 
     assertEquals(m1, m2);
     assertEquals(m1.hashCode(), m2.hashCode());
 
     // Make sure we did compare map fields.
-    b2.getMutableInt32ToInt32Field().put(1, 0);
+    b2.putInt32ToInt32Field(1, 0);
     m2 = b2.build();
     assertFalse(m1.equals(m2));
     // Don't check m1.hashCode() != m2.hashCode() because it's not guaranteed
@@ -652,7 +656,7 @@ public class MapTest extends TestCase {
 
     // Regression test for b/18549190: if a map is a subset of the other map,
     // equals() should return false.
-    b2.getMutableInt32ToInt32Field().remove(1);
+    b2.removeInt32ToInt32Field(1);
     m2 = b2.build();
     assertFalse(m1.equals(m2));
     assertFalse(m2.equals(m1));
@@ -661,20 +665,19 @@ public class MapTest extends TestCase {
   public void testNestedBuilderOnChangeEventPropagation() {
     TestOnChangeEventPropagation.Builder parent =
         TestOnChangeEventPropagation.newBuilder();
-    parent.getOptionalMessageBuilder().getMutableInt32ToInt32Field().put(1, 2);
+    parent.getOptionalMessageBuilder().putInt32ToInt32Field(1, 2);
     TestOnChangeEventPropagation message = parent.build();
     assertEquals(2, message.getOptionalMessage().getInt32ToInt32Field().get(1).intValue());
 
     // Make a change using nested builder.
-    parent.getOptionalMessageBuilder().getMutableInt32ToInt32Field().put(1, 3);
+    parent.getOptionalMessageBuilder().putInt32ToInt32Field(1, 3);
 
     // Should be able to observe the change.
     message = parent.build();
     assertEquals(3, message.getOptionalMessage().getInt32ToInt32Field().get(1).intValue());
 
     // Make another change using mergeFrom()
-    TestMap.Builder other = TestMap.newBuilder();
-    other.getMutableInt32ToInt32Field().put(1, 4);
+    TestMap.Builder other = TestMap.newBuilder().putInt32ToInt32Field(1, 4);
     parent.getOptionalMessageBuilder().mergeFrom(other.build());
 
     // Should be able to observe the change.
@@ -697,8 +700,7 @@ public class MapTest extends TestCase {
     TestMap.Builder testMapBuilder = parentBuilder.getOptionalMessageBuilder();
 
     // Create a map entry message.
-    TestMap.Builder entryBuilder = TestMap.newBuilder();
-    entryBuilder.getMutableInt32ToInt32Field().put(1, 1);
+    TestMap.Builder entryBuilder = TestMap.newBuilder().putInt32ToInt32Field(1, 1);
 
     // Put the entry into the nested builder.
     testMapBuilder.addRepeatedField(
@@ -709,7 +711,7 @@ public class MapTest extends TestCase {
     assertEquals(1, message.getOptionalMessage().getInt32ToInt32Field().size());
 
     // Change the entry value.
-    entryBuilder.getMutableInt32ToInt32Field().put(1, 4);
+    entryBuilder.putInt32ToInt32Field(1, 4);
     testMapBuilder = parentBuilder.getOptionalMessageBuilder();
     testMapBuilder.setRepeatedField(
         intMapField, 0, entryBuilder.getRepeatedField(intMapField, 0));
@@ -796,13 +798,11 @@ public class MapTest extends TestCase {
 
   public void testReflectionApi() throws Exception {
     // In reflection API, map fields are just repeated message fields.
-    TestMap.Builder builder = TestMap.newBuilder();
-    builder.getMutableInt32ToInt32Field().put(1, 2);
-    builder.getMutableInt32ToInt32Field().put(3, 4);
-    builder.getMutableInt32ToMessageField().put(
-        11, MessageValue.newBuilder().setValue(22).build());
-    builder.getMutableInt32ToMessageField().put(
-        33, MessageValue.newBuilder().setValue(44).build());
+    TestMap.Builder builder = TestMap.newBuilder()
+        .putInt32ToInt32Field(1, 2)
+        .putInt32ToInt32Field(3, 4)
+        .putInt32ToMessageField(11, MessageValue.newBuilder().setValue(22).build())
+        .putInt32ToMessageField(33, MessageValue.newBuilder().setValue(44).build());
     TestMap message = builder.build();
 
     // Test getField(), getRepeatedFieldCount(), getRepeatedField().
@@ -872,7 +872,7 @@ public class MapTest extends TestCase {
 
   public void testTextFormat() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     String textData = TextFormat.printToString(message);
@@ -886,7 +886,7 @@ public class MapTest extends TestCase {
 
   public void testDynamicMessage() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     Message dynamicDefaultInstance =
@@ -931,10 +931,11 @@ public class MapTest extends TestCase {
   }
 
   public void testUnknownEnumValues() throws Exception {
-    TestMap.Builder builder = TestMap.newBuilder();
-    builder.getMutableInt32ToEnumFieldValue().put(0, 0);
-    builder.getMutableInt32ToEnumFieldValue().put(1, 1);
-    builder.getMutableInt32ToEnumFieldValue().put(2, 1000);  // unknown value.
+    TestMap.Builder builder = TestMap.newBuilder()
+        .putAllInt32ToEnumFieldValue(newMap(
+            0, 0,
+            1, 1,
+            2, 1000));  // unknown value.
     TestMap message = builder.build();
 
     assertEquals(TestMap.EnumValue.FOO,
@@ -957,7 +958,7 @@ public class MapTest extends TestCase {
     assertEquals(1000, builder.getInt32ToEnumFieldValue().get(2).intValue());
 
     // hashCode()/equals() should take unknown enum values into account.
-    builder.getMutableInt32ToEnumFieldValue().put(2, 1001);
+    builder.putAllInt32ToEnumFieldValue(newMap(2, 1001));
     TestMap message2 = builder.build();
     assertFalse(message.hashCode() == message2.hashCode());
     assertFalse(message.equals(message2));
@@ -971,15 +972,13 @@ public class MapTest extends TestCase {
     EnumDescriptor enumDescriptor = TestMap.EnumValue.getDescriptor();
     FieldDescriptor field = descriptor.findFieldByName("int32_to_enum_field");
 
-    Map<Integer, Integer> data = new HashMap<Integer, Integer>();
-    data.put(0, 0);
-    data.put(1, 1);
-    data.put(2, 1000);  // unknown value.
+    Map<Integer, Integer> data = newMap(
+        0, 0,
+        1, 1,
+        2, 1000); // unknown value
 
-    TestMap.Builder builder = TestMap.newBuilder();
-    for (Map.Entry<Integer, Integer> entry : data.entrySet()) {
-      builder.getMutableInt32ToEnumFieldValue().put(entry.getKey(), entry.getValue());
-    }
+    TestMap.Builder builder = TestMap.newBuilder()
+        .putAllInt32ToEnumFieldValue(data);
 
     // Try to read unknown enum values using reflection API.
     for (int i = 0; i < builder.getRepeatedFieldCount(field); i++) {
@@ -1003,7 +1002,7 @@ public class MapTest extends TestCase {
 
   public void testIterationOrder() throws Exception {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
 
     assertEquals(Arrays.asList("1", "2", "3"),
@@ -1012,7 +1011,7 @@ public class MapTest extends TestCase {
 
   public void testGetMap() {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     TestMap message = builder.build();
     assertEquals(
         message.getStringToInt32Field(),
@@ -1033,7 +1032,7 @@ public class MapTest extends TestCase {
 
   public void testContains() {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     assertMapContainsSetValues(builder);
     assertMapContainsSetValues(builder.build());
   }
@@ -1074,7 +1073,7 @@ public class MapTest extends TestCase {
     TestMap.Builder builder = TestMap.newBuilder();
     assertMapCounts(0, builder);
 
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     assertMapCounts(3, builder);
 
     TestMap message = builder.build();
@@ -1269,7 +1268,7 @@ public class MapTest extends TestCase {
 
   public void testRemove() {
     TestMap.Builder builder = TestMap.newBuilder();
-    setMapValuesUsingMutableMap(builder);
+    setMapValuesUsingAccessors(builder);
     assertEquals(11, builder.getInt32ToInt32FieldOrThrow(1));
     for (int times = 0; times < 2; times++) {
       builder.removeInt32ToInt32Field(1);
@@ -1485,4 +1484,12 @@ public class MapTest extends TestCase {
     map.put(key2, value2);
     return map;
   }
+
+  private static <K, V> Map<K, V> newMap(K key1, V value1, K key2, V value2, K key3, V value3) {
+    Map<K, V> map = new HashMap<K, V>();
+    map.put(key1, value1);
+    map.put(key2, value2);
+    map.put(key3, value3);
+    return map;
+  }
 }
diff --git a/java/core/src/test/java/com/google/protobuf/ParserTest.java b/java/core/src/test/java/com/google/protobuf/ParserTest.java
index 7086912b..8c2e4c26 100644
--- a/java/core/src/test/java/com/google/protobuf/ParserTest.java
+++ b/java/core/src/test/java/com/google/protobuf/ParserTest.java
@@ -46,6 +46,7 @@ import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.InterruptedIOException;
 import junit.framework.TestCase;
 
 /**
@@ -372,4 +373,43 @@ public class ParserTest extends TestCase {
     assertEquals(3, parsingMerge.getExtensionCount(
         TestParsingMergeLite.repeatedExt));
   }
+
+  public void testParseDelimitedFrom_firstByteInterrupted_preservesCause() {
+    try {
+      TestUtil.getAllSet().parseDelimitedFrom(
+          new InputStream() {
+            @Override
+            public int read() throws IOException {
+              throw new InterruptedIOException();
+            }
+          });
+      fail("Expected InterruptedIOException");
+    } catch (Exception e) {
+      assertEquals(InterruptedIOException.class, e.getClass());
+    }
+  }
+
+  public void testParseDelimitedFrom_secondByteInterrupted_preservesCause() {
+    try {
+      TestUtil.getAllSet().parseDelimitedFrom(
+          new InputStream() {
+            private int i;
+
+            @Override
+            public int read() throws IOException {
+              switch (i++) {
+                case 0:
+                  return 1;
+                case 1:
+                  throw new InterruptedIOException();
+                default:
+                  throw new AssertionError();
+              }
+            }
+          });
+      fail("Expected InterruptedIOException");
+    } catch (Exception e) {
+      assertEquals(InterruptedIOException.class, e.getClass());
+    }
+  }
 }