Integrate from internal code base.

1 files changed, 8 insertions, 0 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 859a9e8f..c54da67f 100644
--- a/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
+++ b/java/core/src/main/java/com/google/protobuf/DynamicMessage.java
@@ -526,6 +526,14 @@ public final class DynamicMessage extends AbstractMessage {
           fields.clearField(oldField);
         }
         oneofCases[index] = field;
+      } else if (field.getFile().getSyntax() == Descriptors.FileDescriptor.Syntax.PROTO3) {
+        if (!field.isRepeated()
+            && field.getJavaType() != FieldDescriptor.JavaType.MESSAGE
+            && value.equals(field.getDefaultValue())) {
+          // In proto3, setting a field to its default value is equivalent to clearing the field.
+          fields.clearField(field);
+          return this;
+        }
       }
       fields.setField(field, value);
       return this;