How to retrieve the host name by IP with dnsjava library?

Question

I'm trying to retrieve the host name (or domain) of an IP address with dnsjava library by using a SimpleResolver and the ReverseMap and I wrote the following code:

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.CompletableFuture;

import org.xbill.DNS.Lookup;
import org.xbill.DNS.PTRRecord;
import org.xbill.DNS.Record;
import org.xbill.DNS.Resolver;
import org.xbill.DNS.ReverseMap;
import org.xbill.DNS.SimpleResolver;
import org.xbill.DNS.Type;
import org.xbill.DNS.lookup.LookupResult;
import org.xbill.DNS.lookup.LookupSession;

public class IPToName {

    public static void main(String[] args) throws UnknownHostException {
        findHostNameWithLookup();
        findHostNameWithLookupSession();
    }

    public static void findHostNameWithLookup() throws UnknownHostException {
        Resolver resolver = new SimpleResolver(InetAddress.getByName("208.67.222.222"));//Open DNS server
        Collection<String> hostNames = new ArrayList<>();
        for (Integer type : Arrays.asList(Type.A, Type.AAAA, Type.PTR)) {
            final Lookup lookUp = new Lookup(ReverseMap.fromAddress("151.101.1.69"), type);//Stackoverflow.com server
            lookUp.setResolver(resolver);
            Record[] records = lookUp.run();
            if (records != null) {
                for (int i = 0; i < records.length; i++) {
                    if (records[i] instanceof PTRRecord) {
                        hostNames.add(records[i].rdataToString());
                    }
                }
            }
        }
        hostNames.stream().forEach(System.out::println);
    }

    public static void findHostNameWithLookupSession() throws UnknownHostException {
        LookupSession lookupSession = LookupSession.builder().resolver(
            new SimpleResolver(InetAddress.getByName("208.67.222.222"))
        ).build();
        Collection<CompletableFuture<LookupResult>> hostNamesRetrievers = new ArrayList<>();
        for (Integer type : Arrays.asList(Type.A, Type.AAAA, Type.PTR)) {
            hostNamesRetrievers.add(
                lookupSession.lookupAsync(ReverseMap.fromAddress("151.101.1.69"), type).toCompletableFuture()
            );
        }
        hostNamesRetrievers.stream().forEach(hostNamesRetriever -> {
            try {
                List<Record> records = hostNamesRetriever.join().getRecords();
                if (records != null) {
                    for (Record record : records) {
                        System.out.println(record.rdataToString());
                    }
                }
            } catch (Throwable exc) {
                exc.printStackTrace();
            }
        });
    }

}

But with the method findHostNameWithLookup I receive a null array of records and with the findHostNameWithLookupSession I receive all NoSuchDomainException: considering that the istruction ReverseMap.fromAddress("151.101.1.69") generate the String 69.1.101.151.in-addr.arpa.: does anyone know what's wrong?