code: public Message.Builder getBuilder(Class<? extends TBase<?, ?>> thriftClass) {
      return messageBuilderMap.get(protoMessageType(thriftClass)).clone();
    }
docs: For the given thriftClass, return a Protobufs builder to build a similar protobuf class.
  @param thriftClass The thrift class for which the builder is desired.
  @return a protobuf message builder