title: JPA merge updating all the object from Relationship graph
body: <p>I have a Entity which has a oneToMany relationship with another Entity</p>
  
  <pre><code>@LazyCollection(LazyCollectionOption.FALSE)
  @OneToMany(mappedBy = "entity1", cascade = CascadeType.ALL)
  private List&lt;Entity2&gt; entity2;
  </code></pre>
  
  <p>In Entity2 ManyToOne with Entity1</p>
  
  <pre><code>@ManyToOne(cascade=CascadeType.MERGE)
  @JoinColumn(name = "ENTITY1_ID")
  private Entity1 entity1;
  </code></pre>
  
  <p>Now, we have two instance of Entity1. Every instance have only 1 instance of Entity 2. I want to update one Entity1 object along with Entity2, but if I use </p>
  
  <pre><code>em.merge(Entity1)
  </code></pre>
  
  <p>it will fire two update statement and update both Entity2. But I want to update only the Entity2 associated with this Entity1.</p>
  
  <p>Please advice, what I am missing here.     </p>