是否可以从Helium应用程序中侦听前端事件（onclick / onchange）？
我似乎无法像在Zeppelin笔记本中那样在Helium Appplication中使用Angular，例如：
import org.apache.zeppelin.display.angular.paragraphscope._
import AngularElem._
...
<div><div>.model("myModel").display
...
AngularModel("myModel", "newValue")
因为调用要么得到一个空指针异常（取自日志）：
ERROR [2017-03-19 12:23:16,231] ({pool-1-thread-1} HeliumApplicationFactory.java[run]:283) - java.lang.NullPointerException
org.apache.zeppelin.helium.ApplicationException: java.lang.NullPointerException
at org.apache.zeppelin.helium.HeliumApplicationFactory$RunApplication.run(HeliumApplicationFactory.java:321)
at org.apache.zeppelin.helium.HeliumApplicationFactory$RunApplication.run(HeliumApplicationFactory.java:281)
at org.apache.zeppelin.helium.HeliumApplicationFactory$LoadApplication.run(HeliumApplicationFactory.java:96)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
我知道这是实验性的，但它很酷。
感谢。