ExpansionServer throws exception when port is retrieved after close

[Test worker] ERROR org.apache.beam.runners.fnexecution.jobsubmission.JobServerDriver - Error while closing the Expansion Service.
java.lang.IllegalStateException: Already terminated
	at org.apache.beam.vendor.grpc.v1p13p1.com.google.common.base.Preconditions.checkState(Preconditions.java:444)
	at org.apache.beam.vendor.grpc.v1p13p1.io.grpc.internal.ServerImpl.getPort(ServerImpl.java:174)
	at org.apache.beam.runners.core.construction.expansion.ExpansionServer.getPort(ExpansionServer.java:66)
	at org.apache.beam.runners.fnexecution.jobsubmission.JobServerDriver.stop(JobServerDriver.java:200)
	at sun.reflect.GeneratedMethodAccessor173.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at