code: public static ResourceRecordSet<SOAData> soa(ResourceRecordSet<?> soa, String email, int ttl) {
      SOAData soaData = (SOAData) soa.records().get(0);
      soaData = soaData.toBuilder().serial(soaData.serial() + 1).rname(email).build();
      return ResourceRecordSet.<SOAData>builder()
          .name(soa.name())
          .type("SOA")
          .ttl(ttl)
          .add(soaData)
          .build();
    }
docs: Returns an updated SOA rrset, with an incremented serial number and the specified parameters.