[beam_PreCommit_Java_Cron] [GrpcDataServiceTest] Flake, Multiplexer hanging up

org.apache.beam.runners.fnexecution.data.GrpcDataServiceTest > testMessageReceivedBySingleClientWhenThereAreMultipleClients FAILED
    java.lang.AssertionError at GrpcDataServiceTest.java:105

[grpc-default-executor-2] WARN org.apache.beam.sdk.fn.data.BeamFnDataGrpcMultiplexer - Hanged up for unknown endpoint.
Jan 25, 2019 6:16:02 PM org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.SerializingExecutor run
SEVERE: Exception while executing runnable org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed@41415b8e
java.lang.RuntimeException: org.apache.beam.vendor.grpc.v1p13p1.io.grpc.StatusRuntimeException: CANCELLED: Multiplexer hanging up
	at org.apache.beam.sdk.fn.test.TestStreams.lambda$throwingErrorHandler$0(TestStreams.java:95)
	at org.apache.beam.sdk.fn.test.TestStreams$ForwardingCallStreamObserver.onError(TestStreams.java:144)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.stub.ClientCalls$StreamObserverToCallListenerAdapter.onClose(ClientCalls.java:420)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.PartialForwardingClientCallListener.onClose(PartialForwardingClientCallListener.java:39)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.ForwardingClientCallListener.onClose(ForwardingClientCallListener.java:23)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.ForwardingClientCallListener$SimpleForwardingClientCallListener.onClose(ForwardingClientCallListener.java:40)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.CensusStatsModule$StatsClientInterceptor$1$1.onClose(CensusStatsModule.java:684)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.PartialForwardingClientCallListener.onClose(PartialForwardingClientCallListener.java:39)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.ForwardingClientCallListener.onClose(ForwardingClientCallListener.java:23)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.ForwardingClientCallListener$SimpleForwardingClientCallListener.onClose(ForwardingClientCallListener.java:40)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.CensusTracingModule$TracingClientInterceptor$1$1.onClose(CensusTracingModule.java:403)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:459)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ClientCallImpl.access$300(ClientCallImpl.java:63)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl.close(ClientCallImpl.java:546)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl.access$600(ClientCallImpl.java:467)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:584)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:123)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.beam.vendor.grpc.v1p13p1.io.grpc.StatusRuntimeException: CANCELLED: Multiplexer hanging up
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.Status.asRuntimeException(Status.java:526)
	... 19 more