public Builder addAllExtension(
          java.lang.Iterable<? extends com.google.protobuf.DescriptorProtos.FieldDescriptorProto> values) {
        if (extensionBuilder_ == null) {
          ensureExtensionIsMutable();
          super.addAll(values, extension_);
          onChanged();
        } else {
          extensionBuilder_.addAllMessages(values);
        }
        return this;
      }