code: public boolean isSet(_Fields field) {
      if (field == null) {
        throw new java.lang.IllegalArgumentException();
      }
  
      switch (field) {
      case IPV4:
        return isSetIpv4();
      case PORT:
        return isSetPort();
      case SERVICE_NAME:
        return isSetService_name();
      }
      throw new java.lang.IllegalStateException();
    }
docs: Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise