Fib Manager / API to check for IPv4 or IPv6 prefix returns exception

il-api - 0.3.0.SNAPSHOT | UnknownHostException while checking whether 'IpAddress [_ipv6Address=Ipv6Address [_value=2001:db8:0\
 :2:f816:3eff:fe7b:6e75]]' is an IPv4 address
 java.net.UnknownHostException: IpAddress [_ipv6Address=Ipv6Address [_value=2001:db8:0:2:f816:3eff:fe7b:6e75]]: Name or servic\
 e not known
 at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)[:1.8.0_141]
 at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)[:1.8.0_141]
 at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)[:1.8.0_141]
 at java.net.InetAddress.getAllByName0(InetAddress.java:1276)[:1.8.0_141]
 at java.net.InetAddress.getAllByName(InetAddress.java:1192)[:1.8.0_141]
 at java.net.InetAddress.getAllByName(InetAddress.java:1126)[:1.8.0_141]
 at java.net.InetAddress.getByName(InetAddress.java:1076)[:1.8.0_141]
 at org.opendaylight.genius.mdsalutil.NWUtil.isIpv4Address(NWUtil.java:182)
 at org.opendaylight.netvirt.fibmanager.api.FibHelper.isIpv4Prefix(FibHelper.java:161)
 at org.opendaylight.netvirt.fibmanager.api.FibHelper.isBelongingPrefix(FibHelper.java:210)
 at org.opendaylight.netvirt.neutronvpn.NeutronvpnManager.withdrawPortIpFromVpnIface(NeutronvpnManager.java:764)
 at org.opendaylight.netvirt.neutronvpn.NeutronvpnManager.lambda$removeSubnetFromVpn$1(NeutronvpnManager.java:1438)
 at org.opendaylight.genius.datastoreutils.DataStoreJobCoordinator$MainTask.run(DataStoreJobCoordinator.java:285)[238:\
 org.opendaylight.genius.mdsalutil-api:0.3.0.SNAPSHOT]
 at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1402)[:1.8.0_141]
 at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)[:1.8.0_141]