private com.google.protobuf.SingleFieldBuilder<
          org.bwapi.proxy.messages.BasicTypes.Position, org.bwapi.proxy.messages.BasicTypes.Position.Builder, org.bwapi.proxy.messages.BasicTypes.PositionOrBuilder> 
          getCenterFieldBuilder() {
        if (centerBuilder_ == null) {
          centerBuilder_ = new com.google.protobuf.SingleFieldBuilder<
              org.bwapi.proxy.messages.BasicTypes.Position, org.bwapi.proxy.messages.BasicTypes.Position.Builder, org.bwapi.proxy.messages.BasicTypes.PositionOrBuilder>(
                  center_,
                  getParentForChildren(),
                  isClean());
          center_ = null;
        }
        return centerBuilder_;
      }