com/sun/jndi/rmi/registry/RegistryContext/UnbindIdempotent.java failed with "Port already in use".

----------System.err:(32/2213)----------
java.rmi.server.ExportException: Port already in use: 34687; nested exception is:
java.net.BindException: Address already in use (Bind failed)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.listen(TCPTransport.java:340)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.exportObject(TCPTransport.java:248)
at java.rmi/sun.rmi.transport.tcp.TCPEndpoint.exportObject(TCPEndpoint.java:411)
at java.rmi/sun.rmi.transport.LiveRef.exportObject(LiveRef.java:147)
at java.rmi/sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:232)
at java.rmi/sun.rmi.registry.RegistryImpl.setup(RegistryImpl.java:157)
at java.rmi/sun.rmi.registry.RegistryImpl.<init>(RegistryImpl.java:142)
at java.rmi/java.rmi.registry.LocateRegistry.createRegistry(LocateRegistry.java:203)
at TestLibrary.createRegistryOnUnusedPort(TestLibrary.java:412)
at UnbindIdempotent.main(UnbindIdempotent.java:45)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:537)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:226)
at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.net.BindException: Address already in use (Bind failed)
at java.base/java.net.PlainSocketImpl.socketBind(Native Method)
at java.base/java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:437)
at java.base/java.net.ServerSocket.bind(ServerSocket.java:381)
at java.base/java.net.ServerSocket.<init>(ServerSocket.java:243)
at java.base/java.net.ServerSocket.<init>(ServerSocket.java:135)
at java.rmi/sun.rmi.transport.tcp.TCPDirectSocketFactory.createServerSocket(TCPDirectSocketFactory.java:45)
at java.rmi/sun.rmi.transport.tcp.TCPEndpoint.newServerSocket(TCPEndpoint.java:666)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.listen(TCPTransport.java:329)
... 15 more