Customer has tested with the test case in JDK-8075484 and found that
they are still seeing the errors when using 8u231
i.e. they are seeing "Should never happen: A is unresponsive"
The customer tested with the attached native tests. Both the poll (which mimics the JDK's behaviour) and the socket timeout option (which does not) reproduced the issue. The underlying cause appears to be related to the customers infrastructure, and not a JDK problem.