public OFOxm<IPv4Address> getCanonical() {
   if (IPv4Address.NO_MASK.equals(mask)) {
     return new OFOxmArpTpaVer12(value);
   } else if (IPv4Address.FULL_MASK.equals(mask)) {
     return null;
   } else {
     return this;
   }
 }
 public OFOxm<IPv4Address> getCanonical() {
   if (IPv4Address.NO_MASK.equals(mask)) {
     return new OFOxmTunnelIpv4SrcVer13(value);
   } else if (IPv4Address.FULL_MASK.equals(mask)) {
     return null;
   } else {
     return this;
   }
 }