public Builder mergeCarrier(org.bwapi.proxy.messages.GameMessages.UnitId value) {
        if (carrierBuilder_ == null) {
          if (((bitField1_ & 0x00400000) == 0x00400000) &&
              carrier_ != org.bwapi.proxy.messages.GameMessages.UnitId.getDefaultInstance()) {
            carrier_ =
              org.bwapi.proxy.messages.GameMessages.UnitId.newBuilder(carrier_).mergeFrom(value).buildPartial();
          } else {
            carrier_ = value;
          }
          onChanged();
        } else {
          carrierBuilder_.mergeFrom(value);
        }
        bitField1_ |= 0x00400000;
        return this;
      }