Fixed NPE in FD_SOCK2 (https://issues.redhat.com/browse/JGRP-2707)

Author: belaban

src/org/jgroups/protocols/FD_SOCK2.java

@@ -442,6 +442,8 @@ protected boolean connectTo(IpAddress dest, Address logical_addr) {
     /** Returns the physical addresses for a in range [a+offset..a+offset+port_range */
     protected List<IpAddress> getPhysicalAddresses(Address a) {
         IpAddress pa=(IpAddress)down_prot.down(new Event(Event.GET_PHYSICAL_ADDRESS, a));
+        if(pa == null)
+            return Collections.emptyList();
         InetAddress addr=pa.getIpAddress();
         int actual_port=pa.getPort();
         int[] bind_ports=computeBindPorts(actual_port);