[14] 8237368: Problem with NullPointerException in RMI TCPEndpoint.read

[Roger Riggs]

Please review this fix to correctly allow null for a custom socket 
factory in TCPEndpoint.

issue: https://bugs.openjdk.java.net/browse/JDK-8237368
webrev: http://cr.openjdk.java.net/~rriggs/webrev-proxy-8237368/

Thanks, Roger