It has been observed once on Linux X64. Looks to be intermittent.

Please refer to the output below:
----------messages:(4/168)----------
command: main SessionTimeOutTests
reason: User specified action: run main/othervm SessionTimeOutTests
Mode: othervm [/othervm specified]
elapsed time (seconds): 0.769
----------configuration:(0/0)----------
----------System.out:(0/0)----------
----------System.err:(48/3453)----------
Server died...
java.net.SocketException: Address already in use (Listen failed)
at java.base/java.net.PlainSocketImpl.socketListen(Native Method)
at java.base/java.net.AbstractPlainSocketImpl.listen(AbstractPlainSocketImpl.java:449)
at java.base/java.net.ServerSocket.bind(ServerSocket.java:382)
at java.base/java.net.ServerSocket.<init>(ServerSocket.java:243)
at java.base/java.net.ServerSocket.<init>(ServerSocket.java:187)
at java.base/javax.net.ssl.SSLServerSocket.<init>(SSLServerSocket.java:136)
at java.base/sun.security.ssl.SSLServerSocketImpl.<init>(SSLServerSocketImpl.java:116)
at java.base/sun.security.ssl.SSLServerSocketFactoryImpl.createServerSocket(SSLServerSocketFactoryImpl.java:79)
at SessionTimeOutTests.doServerSide(SessionTimeOutTests.java:114)
at SessionTimeOutTests$1.run(SessionTimeOutTests.java:443)
java.net.ConnectException: Connection refused (Connection refused)
at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:400)
at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:243)
at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:225)
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:402)
at java.base/java.net.Socket.connect(Socket.java:591)
at java.base/sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:657)
at java.base/sun.security.ssl.SSLSocketImpl.<init>(SSLSocketImpl.java:422)
at java.base/sun.security.ssl.SSLSocketFactoryImpl.createSocket(SSLSocketFactoryImpl.java:88)
at SessionTimeOutTests.doClientSide(SessionTimeOutTests.java:164)
at SessionTimeOutTests.startClient(SessionTimeOutTests.java:488)
at SessionTimeOutTests.<init>(SessionTimeOutTests.java:364)
at SessionTimeOutTests.main(SessionTimeOutTests.java:328)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:543)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:110)
at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.net.SocketException: Address already in use (Listen failed)
at java.base/java.net.PlainSocketImpl.socketListen(Native Method)
at java.base/java.net.AbstractPlainSocketImpl.listen(AbstractPlainSocketImpl.java:449)
at java.base/java.net.ServerSocket.bind(ServerSocket.java:382)
at java.base/java.net.ServerSocket.<init>(ServerSocket.java:243)
at java.base/java.net.ServerSocket.<init>(ServerSocket.java:187)
at java.base/javax.net.ssl.SSLServerSocket.<init>(SSLServerSocket.java:136)
at java.base/sun.security.ssl.SSLServerSocketImpl.<init>(SSLServerSocketImpl.java:116)
at java.base/sun.security.ssl.SSLServerSocketFactoryImpl.createServerSocket(SSLServerSocketFactoryImpl.java:79)
at SessionTimeOutTests.doServerSide(SessionTimeOutTests.java:114)
at SessionTimeOutTests$1.run(SessionTimeOutTests.java:443)