pr/3356 fails in the Apex WordCountTest. The failed test is here <https://builds.apache.org/job/beam_PreCommit_Java_MavenInstall/12829/org.apache.beam$beam-runners-apex/testReport/org.apache.beam.runners.apex.examples/WordCountTest/testWordCountExample/> :
Upon debugging, it looks like this is likely a problem in the Apex runner itself. A ParDo calls output(), and that triggers an exception thrown from inside the Apex runner. The Apex runner calls emit on a DefaultOutputPort (ApexParDoOperator.java:275), and that throws an exception inside of verifyOperatorThread(). I'm going to ignore this failure for now as it seems unrelated to my PR, but does someone want to take a look? Reuven
