public Builder clearChunk() {
      if (chunkBuilder_ == null) {
        if (fileHandleOrBufferCase_ == 2) {
          fileHandleOrBufferCase_ = 0;
          fileHandleOrBuffer_ = null;
          onChanged();
        }
      } else {
        if (fileHandleOrBufferCase_ == 2) {
          fileHandleOrBufferCase_ = 0;
          fileHandleOrBuffer_ = null;
        }
        chunkBuilder_.clear();
      }
      return this;
    }
public Builder clearChunk()