Hibernate binding returns null on insert

I'm here to get help because I've been searching the internet for a few hours without finding my answers. Maybe someone here will have a solution to my problem.

I'm new with spring boot, so don't be too mean to me, I probably missed some information in the documentation.
I'm trying to add data to my database with a json file that looks like this one.
Everything works correctly up to the OneToMany relationship and vice versa ManyToOne (I followed the doc here).
I put Cascade.ALL to propagate to entities.
As you can see, Hibernate makes a binding with a null value, as if it had never been inserted whereas it seems to be at the previous step.
A lot of topics deal with this problem, and for many of them they have been solved with the null = false option, but it doesn't work for me.

Information:
A contact can have multiple email addresses, and an email address belongs to only one contact.

My code :

Emails

@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Entity
@Table(name = "Email")
public class Email implements Serializable {

    @Id
    @GeneratedValue
    @Column(name = "idEmail")
    private int id;

    @Column(name = "Email")
    @JsonProperty("mail")
    private String email;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "Contact_idContact")
    private Contact contact;
}

Contact

@Entity
@Table(name = "Contact")
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
public class Contact implements Serializable {

    @GeneratedValue
    @Id
    @Column(name = "idContact", nullable = false, unique = true)
    private int id;

    @Column(name = "Nom")
    private String nom;

    @Column(name = "Prenom")
    private String prenom;

    @Column(name = "Mobile")
    private String mobile;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "contact")
    private Set<Email> emails = new HashSet<>();
}

My json post :

{
"contacts": [
    {
      "nom": "myName",
      "prenom": "MyFirstName",
      "mobile": "06666666666",
      "emails": [
        {
          "mail": "mail1@test.com"
        },
	      {
          "mail": "mail2@test.com"
        }
      ],
    }
  ]
}

POST Method

 @PostMapping("/add")
    public ResponseEntity<Void> addContact(@RequestBody Contact contact) {

        Contact contact1 = contactService.save(contact);
        URI location = ServletUriComponentsBuilder
                .fromCurrentRequest()
                .path("/{id}")
                .buildAndExpand(contact1.getId())
                .toUri();
        return ResponseEntity.created(location).build();
    }

Error:

2020-10-15 16:40:16.501 DEBUG 13608 --- [nio-9000-exec-2] org.hibernate.SQL                        : insert into Contact (Mobile, Nom, Prenom, idContact) values (?, ?, ?, ?)
2020-10-15 16:40:16.502 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [1] as [VARCHAR] - [06666666666]
2020-10-15 16:40:16.503 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [2] as [VARCHAR] - [MyName]
2020-10-15 16:40:16.504 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [3] as [VARCHAR] - [MyFirstName]
2020-10-15 16:40:16.505 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [4] as [INTEGER] - [46]
2020-10-15 16:40:16.510 DEBUG 13608 --- [nio-9000-exec-2] org.hibernate.SQL                        : insert into Email (Contact_idContact, Email, idEmail) values (?, ?, ?)
2020-10-15 16:40:16.511 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [1] as [INTEGER] - [null]
2020-10-15 16:40:16.512 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [2] as [VARCHAR] - [mail1@test.com]
2020-10-15 16:40:16.512 TRACE 13608 --- [nio-9000-exec-2] o.h.type.descriptor.sql.BasicBinder      : binding parameter [3] as [INTEGER] - [47]
2020-10-15 16:40:16.542  WARN 13608 --- [nio-9000-exec-2] o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 1048, SQLState: 23000
2020-10-15 16:40:16.542 ERROR 13608 --- [nio-9000-exec-2] o.h.engine.jdbc.spi.SqlExceptionHelper   : Column 'Contact_idContact' cannot be null
2020-10-15 16:40:16.636 ERROR 13608 --- [nio-9000-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause

In this case, Contact_idContact should be 46 as inserted.

What's wrong with it?

I resolved my problem. I forgot a CascadeType.ALL in Email.java.