code: public int getPortNumber() {
          if (tc.isEntryEnabled())
              SibTr.entry(this, tc, "getPortNumber");
          if (tc.isEntryEnabled())
              SibTr.exit(this, tc, "getPortNumber", "" + portNumber);
          return portNumber;
      }
docs: Returns the port number associated with this listener port.
  
  @see ListenerPort#getPortNumber()