When setting ip_mcast=false in UDP, on reception of a message, the destination is a unicast address. However, it should be either null, or a multicast address. This might cause problems in cases where msg.getDest() is called. If the destination field is used as a key into a hashmap, this would be incorrect.
TASK 1: verify that this leads to incorrect behavior
TASK 2: fix this, to make dest null when ip_mcast=false