private com.google.protobuf.SingleFieldBuilder<
          org.bwapi.proxy.messages.TerrainMessages.Polygon, org.bwapi.proxy.messages.TerrainMessages.Polygon.Builder, org.bwapi.proxy.messages.TerrainMessages.PolygonOrBuilder> 
          getPolygonFieldBuilder() {
        if (polygonBuilder_ == null) {
          polygonBuilder_ = new com.google.protobuf.SingleFieldBuilder<
              org.bwapi.proxy.messages.TerrainMessages.Polygon, org.bwapi.proxy.messages.TerrainMessages.Polygon.Builder, org.bwapi.proxy.messages.TerrainMessages.PolygonOrBuilder>(
                  polygon_,
                  getParentForChildren(),
                  isClean());
          polygon_ = null;
        }
        return polygonBuilder_;
      }