public Builder setMessageType(
          int index, com.google.protobuf.DescriptorProtos.DescriptorProto.Builder builderForValue) {
        if (messageTypeBuilder_ == null) {
          ensureMessageTypeIsMutable();
          messageType_.set(index, builderForValue.build());
          onChanged();
        } else {
          messageTypeBuilder_.setMessage(index, builderForValue.build());
        }
        return this;
      }