title: Nested exception is javax.persistence.EntityNotFoundException
body: <p>I'm using spring boot and and spring data in my project and i have two classes:</p>
  
  <pre><code>class Mission implements Serializable { private static final long 
  serialVersionUID = 1L;
  @Id
  @GeneratedValue( strategy = GenerationType.IDENTITY )
  private Long              id;
  private String            departure;
  private String            arrival;
  private Boolean           isFreeWayEnabled;
  @OneToMany( mappedBy = "mission" )
  private List&lt;Station&gt;     stations;
  // getters and setters
  }
  </code></pre>
  
  <p>and the second class is :</p>
  
  <pre><code>@Entity
  public class Station implements Serializable {
  
  private static final long serialVersionUID = 1L;
  
  @Id
  @GeneratedValue( strategy = GenerationType.IDENTITY )
  private Long              id;
  private String            station;
  
  @ManyToOne( fetch = FetchType.LAZY )
  @JsonBackReference
  private Mission           mission;
  //getters and setters
   }
  </code></pre>
  
  <p>Methode which add Mission:</p>
  
  <pre><code>public Mission addMision( Mission mission ) {
  // TODO Auto-generated method stub
  // Mission mission = getMissionById( mission.getId() );
  for ( Station station : mission.getStations() ) {
      station.setMission( mission );
      stationRepository.save( station );
  }
  return missionRepository.save( mission );
  }
  </code></pre>
  
  <p>when i tried to add a new Mission it gives this error :</p>
  
  <blockquote>
    <p>"Unable to find com.carpooling.entity.Station with id 2; nested exception is javax.persistence.EntityNotFoundException: Unable to find com.carpooling.entity.Station with id 2"</p>
  </blockquote>
  
  <p>heres the JSON object Sent:</p>
  
  <blockquote>
    <p>{"departure":"fff","arrival":"ffff","isFreeWayEnabled":false,"stations":[{"id":1},{"id":2}]}</p>
  </blockquote>