1 files changed, 25 insertions, 10 deletions
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 e6358c3b..a6a774b7 100644
--- a/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
+++ b/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
@@ -30,11 +30,12 @@
 
 package com.google.protobuf;
 
+import static com.google.protobuf.Internal.checkNotNull;
+
 import com.google.protobuf.Descriptors.Descriptor;
 import com.google.protobuf.Descriptors.EnumValueDescriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
 import com.google.protobuf.Descriptors.OneofDescriptor;
-
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Collections;
@@ -338,6 +339,20 @@ public final class DynamicMessage extends AbstractMessage {
       this.fields = FieldSet.newFieldSet();
       this.unknownFields = UnknownFieldSet.getDefaultInstance();
       this.oneofCases = new FieldDescriptor[type.toProto().getOneofDeclCount()];
+      // A MapEntry has all of its fields present at all times.
+      if (type.getOptions().getMapEntry()) {
+        populateMapEntry();
+      }
+    }
+
+    private void populateMapEntry() {
+      for (FieldDescriptor field : type.getFields()) {
+        if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+          fields.setField(field, getDefaultInstance(field.getMessageType()));
+        } else {
+          fields.setField(field, field.getDefaultValue());
+        }
+      }
     }
 
     // ---------------------------------------------------------------
@@ -350,6 +365,10 @@ public final class DynamicMessage extends AbstractMessage {
       } else {
         fields.clear();
       }
+      // A MapEntry has all of its fields present at all times.
+      if (type.getOptions().getMapEntry()) {
+        populateMapEntry();
+      }
       unknownFields = UnknownFieldSet.getDefaultInstance();
       return this;
     }
@@ -589,9 +608,8 @@ public final class DynamicMessage extends AbstractMessage {
 
     @Override
     public Builder setUnknownFields(UnknownFieldSet unknownFields) {
-      if (getDescriptorForType().getFile().getSyntax()
-          == Descriptors.FileDescriptor.Syntax.PROTO3) {
-        // Proto3 discards unknown fields.
+      if (getDescriptorForType().getFile().getSyntax() == Descriptors.FileDescriptor.Syntax.PROTO3
+          && CodedInputStream.getProto3DiscardUnknownFieldsDefault()) {
         return this;
       }
       this.unknownFields = unknownFields;
@@ -600,9 +618,8 @@ public final class DynamicMessage extends AbstractMessage {
 
     @Override
     public Builder mergeUnknownFields(UnknownFieldSet unknownFields) {
-      if (getDescriptorForType().getFile().getSyntax()
-          == Descriptors.FileDescriptor.Syntax.PROTO3) {
-        // Proto3 discards unknown fields.
+      if (getDescriptorForType().getFile().getSyntax() == Descriptors.FileDescriptor.Syntax.PROTO3
+          && CodedInputStream.getProto3DiscardUnknownFieldsDefault()) {
         return this;
       }
       this.unknownFields =
@@ -631,9 +648,7 @@ public final class DynamicMessage extends AbstractMessage {
     /** Verifies that the value is EnumValueDescriptor and matches Enum Type. */
     private void ensureSingularEnumValueDescriptor(
         FieldDescriptor field, Object value) {
-      if (value == null) {
-        throw new NullPointerException();
-      }
+      checkNotNull(value);
       if (!(value instanceof EnumValueDescriptor)) {
         throw new IllegalArgumentException(
           "DynamicMessage should use EnumValueDescriptor to set Enum Value.");