title: Spring Data update mongodb Document with DBRF lazy attribute
body: <p>I want to update a MongoDB document containing a dbrf lazy attribute using spring data.
  First of all, I load the existing document, I change the attributes I want and after that, I call @Repository save method, but when I check the document in MongoDB the dbrf lazy attribute is null.</p>
  
  <p>I tried to load the attribute before by calling getAttribute, but that doesn't fix the problem.</p>
  
  <p>Someone could help me?
  Thanks</p>
  
  <p>I have the Collection below:</p>
  
  <pre><code>@Data
  @Document(collection = "calendriers")
  public class CalendrierEntity {
  
      @Id
      @AutoGenerate(SequanceKey.CALENDRIER)
      private Long id;
  
      @NotNul 
      private String label;
  
      @NotNull
      private HorairesEntity horairesEntity;
  
      @DBRef(lazy = true)
      @CascadeSave
      @Getter(AccessLevel.NONE)
      private List&lt;AbsenceEntity&gt; absenceEntities;
  }
  </code></pre>
  
  <p>and the repository bellow :</p>
  
  <pre><code>@Repository
  public interface AbsenceRepository extends MongoRepository&lt;CalendrierEntity, Long&gt; {
  
      AbsenceEntity findById(Long enfantId, LocalDate localDate);
  }
  </code></pre>
  
  <p>I have calendrier document with Id 1L and want to update his label.
  The calendrier document have allready a list of Absences.</p>
  
  <p>this my code to update the label.</p>
  
  <pre><code>@Transactional
  public void updateLabelCalendrier(Long id, String label){
  CalendrierEntity calendrier  = calenderRepository.findById(1L);
  calendrier.setLabel(label);
  calenderRepository.save(calendrier);
  }
  </code></pre>
  
  <p>but when i check data in mongodb, i have the new label but my list of absences became null.</p>