I already went through the link: <https://jira.spring.io/browse/DATAMONGO-1107> and also I dont see option to set `spring.data.mongodb.persist-null-fields=true` in *application.properties* file.

Spring Data Mongo doesn't even persist a field having value null. How to allow to save null value if I want to do so ?

Person.java

```
@Builder
@Data
@AllArgsConstructor
@NoArgsConstructor
@Document
public class Person {
    private String id;
    private String firstName;
    private String lastName;
    private String emailId;
    @Field
    private List<Hobbies> hobbies;
}

```

Hobbies.java

```
@Builder
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Hobbies {
    private String interest;
    private String sports;
}

```

save() - This method doesn't persist data.

```
private void savePersons() {
        Hobbies hobbies1 = Hobbies.builder().interest("Indoor").sports("Chess").build();
        Hobbies hobbies2 = Hobbies.builder().interest("Loveoor").sports("Table Tennis").build();
        Hobbies hobbies3 = Hobbies.builder().interest("Gamedoor").sports("Cricket").build();
        Hobbies hobbies4 = Hobbies.builder().interest("Happydoor").sports("Lawn Tennis").build();

        Person john = Person.builder().firstName("John")
                .emailId("john.kerr@gmail.com").hobbies(Arrays.asList(hobbies1, hobbies2)).build();

        Person neha = Person.builder().firstName("Neha").lastName("Parate")
                .emailId("john.kerr@gmail.com").hobbies(Arrays.asList(hobbies1, hobbies2, hobbies4)).build();

        repository.saveAll(Arrays.asList(john, neha));
    }

```

*I dont see lastName has been saved in the document.* Also, how to save Date as null value?