When running chart samples (some, not all), the following messages spit out on the console:

 java -cp ./sdk/rt/lib/ext/jfxrt.jar:./apps/samples/Ensemble8.jar ensemble.EnsembleApp
Warning! The following property doesn't have corresponding controller: PlaygroundProperty{fieldName=xAxis, propertyName=side, properties={}}
Warning! The following property doesn't have corresponding controller: PlaygroundProperty{fieldName=yAxis, propertyName=side, properties={}}