NetworkServerControl.start() should throw an exception and not just print exceptions if the server fails to start

NetworkServerControl.start() will not throw an exception if another server is already running on the same port. I am not sure but think perhaps this was changed at one point to accomodate the derby.drda.startNetworkServer property so that the embedded server could continue to boot even if the network server failed to start, but I think this is wrong for normal usage.

http://www.nabble.com/Questions-about-Network-Server-API-Behavior-p5055814.html