Flink test flake in ReadSourceStreamingITCase

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.792 sec - in org.apache.beam.runners.flink.SideInputITCase
Running org.apache.beam.runners.flink.ReadSourceStreamingITCase
Pipeline execution failed
java.lang.RuntimeException: Pipeline execution failed
	at org.apache.beam.runners.flink.FlinkPipelineRunner.run(FlinkPipelineRunner.java:119)
	at org.apache.beam.runners.flink.FlinkPipelineRunner.run(FlinkPipelineRunner.java:51)
	at org.apache.beam.sdk.Pipeline.run(Pipeline.java:182)
	at org.apache.beam.runners.flink.ReadSourceStreamingITCase.runProgram(ReadSourceStreamingITCase.java:70)
	at org.apache.beam.runners.flink.ReadSourceStreamingITCase.testProgram(ReadSourceStreamingITCase.java:53)
	at org.apache.flink.streaming.util.StreamingProgramTestBase.testJob(StreamingProgramTestBase.java:85)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)
Caused by: org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
	at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$7.apply$mcV$sp(JobManager.scala:714)
	at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$7.apply(JobManager.scala:660)
	at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$7.apply(JobManager.scala:660)
	at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
	at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
	at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:41)
	at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:401)
	at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
	at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.pollAndExecAll(ForkJoinPool.java:1253)
	at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1346)
	at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
	at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: java.lang.NullPointerException
	at org.apache.beam.runners.flink.translation.wrappers.SourceInputFormat.nextRecord(SourceInputFormat.java:143)
	at org.apache.flink.streaming.api.functions.source.FileSourceFunction.run(FileSourceFunction.java:124)
	at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:78)
	at org.apache.flink.streaming.runtime.tasks.SourceStreamTask.run(SourceStreamTask.java:56)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:224)
	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:559)
	at java.lang.Thread.run(Thread.java:745)
Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.989 sec <<< FAILURE! - in org.apache.beam.runners.flink.ReadSourceStreamingITCase
testJob(org.apache.beam.runners.flink.ReadSourceStreamingITCase)  Time elapsed: 0.988 sec  <<< FAILURE!
java.lang.AssertionError: Error while calling the test program: Pipeline execution failed
	at org.junit.Assert.fail(Assert.java:88)
	at org.apache.flink.streaming.util.StreamingProgramTestBase.testJob(StreamingProgramTestBase.java:90)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)

Running org.apache.beam.runners.flink.WriteSinkITCase
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.994 sec - in org.apache.beam.runners.flink.WriteSinkITCase
Running org.apache.beam.runners.flink.JoinExamplesITCase
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.957 sec - in org.apache.beam.runners.flink.JoinExamplesITCase
Running org.apache.beam.runners.flink.TfIdfITCase
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.509 sec - in org.apache.beam.runners.flink.TfIdfITCase
Running org.apache.beam.runners.flink.RemoveDuplicatesITCase
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.777 sec - in org.apache.beam.runners.flink.RemoveDuplicatesITCase