public static void main(String[] args) {
  CodecRegistry pojoCodecRegistry = fromRegistries(MongoClient.getDefaultCodecRegistry(),
      fromProviders(PojoCodecProvider.builder().automatic(true).build()));

  MongoClientSettings settings = MongoClientSettings.builder()
      .codecRegistry(pojoCodecRegistry)
      .build();

  com.mongodb.client.MongoClient mongoClient = MongoClients.create(settings);
  MongoDatabase database = mongoClient.getDatabase("test");
  database = database.withCodecRegistry(pojoCodecRegistry);
  MongoCollection<FieldDotsTester> coll = database.getCollection("dots_test", FieldDotsTester.class);
  coll = coll.withCodecRegistry(pojoCodecRegistry);

  //This line fails
  coll.insertOne(new FieldDotsTester("d.t", "1"));

  if (!coll.find().first().data.keySet().iterator().next().equals("d.t")) {
    throw new RuntimeException();
  }
}

import java.util.HashMap;
import java.util.Map;

public class FieldDotsTester {
  public Map<String, String> data;

  public FieldDotsTester() {}

  public FieldDotsTester(String k, String v) {
    data = new HashMap<>();
    data.put(k, v);
  }
}