使用FeatureCollection.fromJson​（）加载geojson 数据到 arcgis android里，无法显示地图

 var  featureCollection = FeatureCollection.fromJson(builderStr.toString())
 var featureCollectionLayer = FeatureCollectionLayer(featureCollection)
            featureCollectionLayer.loadAsync()
            featureCollectionLayer.addDoneLoadingListener {
                if (featureCollectionLayer.loadStatus == LoadStatus.LOADED) {
                    featureCollectionLayer.isVisible = true
//                    dataMapView.setViewpointGeometryAsync(featureCollectionLayer.fullExtent)
                    dataMapView.map.operationalLayers.add(featureCollectionLayer)
                    Log.e("operationalLayers", dataMapView.map.operationalLayers.size.toString())
                }
            }

运行结果及报错内容

地图无法显示，但size = 1