code: public static byte[] convertFromIPv4MappedAddress(final byte[] addr) { // NOPMD
      if (isIPv4MappedAddress(addr)) {
        final byte[] newAddr = new byte[INADDR4SZ];
        System.arraycopy(addr, 12, newAddr, 0, INADDR4SZ);
        return newAddr;
      }
      return null;
    }
docs: Convert IPv4-Mapped address to IPv4 address. Both input and returned value are in network order
  binary form.
  
  @param addr a representing an IPv4-Mapped address in textual format
  
  @return a byte array representing the IPv4 numeric address