1 files changed, 36 insertions, 12 deletions

diff --git a/java/core/src/main/java/com/google/protobuf/FieldSet.java b/java/core/src/main/java/com/google/protobuf/FieldSet.java
index 47924b65..c09daa32 100644
--- a/java/core/src/main/java/com/google/protobuf/FieldSet.java
+++ b/java/core/src/main/java/com/google/protobuf/FieldSet.java
@@ -30,8 +30,9 @@
 
 package com.google.protobuf;
 
-import com.google.protobuf.LazyField.LazyIterator;
+import static com.google.protobuf.Internal.checkNotNull;
 
+import com.google.protobuf.LazyField.LazyIterator;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -101,6 +102,11 @@ final class FieldSet<FieldDescriptorType extends
   @SuppressWarnings("rawtypes")
   private static final FieldSet DEFAULT_INSTANCE = new FieldSet(true);
 
+  /** Returns {@code true} if empty, {@code false} otherwise. */
+  boolean isEmpty() {
+    return fields.isEmpty();
+  }
+
   /** Make this FieldSet immutable from this point forward. */
   @SuppressWarnings("unchecked")
   public void makeImmutable() {
@@ -121,6 +127,25 @@ final class FieldSet<FieldDescriptorType extends
     return isImmutable;
   }
 
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+
+    if (!(o instanceof FieldSet)) {
+      return false;
+    }
+
+    FieldSet<?> other = (FieldSet<?>) o;
+    return fields.equals(other.fields);
+  }
+
+  @Override
+  public int hashCode() {
+    return fields.hashCode();
+  }
+
   /**
    * Clones the FieldSet. The returned FieldSet will be mutable even if the
    * original FieldSet was immutable.
@@ -201,6 +226,7 @@ final class FieldSet<FieldDescriptorType extends
     return fields.entrySet().iterator();
   }
 
+
   /**
    * Useful for implementing
    * {@link Message#hasField(Descriptors.FieldDescriptor)}.
@@ -365,9 +391,7 @@ final class FieldSet<FieldDescriptorType extends
    */
   private static void verifyType(final WireFormat.FieldType type,
                                  final Object value) {
-    if (value == null) {
-      throw new NullPointerException();
-    }
+    checkNotNull(value);
 
     boolean isValid = false;
     switch (type.getJavaType()) {
@@ -474,7 +498,7 @@ final class FieldSet<FieldDescriptorType extends
   }
 
   /**
-   * Like {@link Message.Builder#mergeFrom(Message)}, but merges from another 
+   * Like {@link Message.Builder#mergeFrom(Message)}, but merges from another
    * {@link FieldSet}.
    */
   public void mergeFrom(final FieldSet<FieldDescriptorType> other) {
@@ -619,10 +643,11 @@ final class FieldSet<FieldDescriptorType extends
    *               {@link Message#getField(Descriptors.FieldDescriptor)} for
    *               this field.
    */
-  private static void writeElement(final CodedOutputStream output,
-                                   final WireFormat.FieldType type,
-                                   final int number,
-                                   final Object value) throws IOException {
+  static void writeElement(
+      final CodedOutputStream output,
+      final WireFormat.FieldType type,
+      final int number,
+      final Object value) throws IOException {
     // Special case for groups, which need a start and end tag; other fields
     // can just use writeTag() and writeFieldNoTag().
     if (type == WireFormat.FieldType.GROUP) {
@@ -785,9 +810,8 @@ final class FieldSet<FieldDescriptorType extends
    *               {@link Message#getField(Descriptors.FieldDescriptor)} for
    *               this field.
    */
-  private static int computeElementSize(
-      final WireFormat.FieldType type,
-      final int number, final Object value) {
+  static int computeElementSize(
+      final WireFormat.FieldType type, final int number, final Object value) {
     int tagSize = CodedOutputStream.computeTagSize(number);
     if (type == WireFormat.FieldType.GROUP) {
       // Only count the end group tag for proto2 messages as for proto1 the end