RFR[7164518]: 'No PortUnreachableException when connecting to a non-existing DatagramSocket (mac)'

[Patrick Concannon]

Hi,

Could someone please review my fix for JDK-7164518 —  'No PortUnreachableException when connecting to a non-existing DatagramSocket (Mac)’ ?

This test failed with a `SocketTimeoutException` instead of the expected `PortUnreachableException`. However, the issue causing this has been resolved in JDK 15 with the new implementation of DatagramSocket, and can now be taken off the ProblemList. 

This fix adds the option `-Djdk.net.usePlainDatagramSocketImpl=false` to the test to ensure that it only uses the new implementation and therefore no longer fails. 

issue: https://bugs.openjdk.java.net/browse/JDK-7164518
webrev: http://cr.openjdk.java.net/~pconcannon/7164518/webrevs/webrev.00/


Kind regards,
Patrick