public Builder setSource(
          org.bwapi.proxy.messages.GameMessages.UnitId.Builder builderForValue) {
        if (sourceBuilder_ == null) {
          source_ = builderForValue.build();
          onChanged();
        } else {
          sourceBuilder_.setMessage(builderForValue.build());
        }
        bitField0_ |= 0x00000008;
        return this;
      }