title: Graphdiff is removing entities
body: <p>I have the following entities:  </p>
  
  <pre><code>public class Profile
  {
      [Required]
      public string Name { get; set; }
  
      [Required]
      public string Description { get; set; }
  
      [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
      public int ID { get; set; }
  
      public IList&lt;Functionality&gt; Functionalities { get; set; }
  }  
  </code></pre>
  
  <p>and  </p>
  
  <pre><code>public class Functionality
  {
      [Required]
      public string Name { get; set; }
  
      [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
      public int ID { get; set; }
  }  
  </code></pre>
  
  <p>In my service method, when I try the following, it removes from the database the Functionality objects that are not in Profile's Functionalities list:  </p>
  
  <pre><code>(...)
  var databaseFunctionalities = this
                               .Repository
                               .GetByIds&lt;Functionality&gt;(profile
                                                       .Functionalities
                                                       .ToIdList());
  profile.Functionalities.Clear();
  profile.Functionalities.AddRange(databaseFunctionalities);
  
  ((BaseRepository)this.Repository)
  .UpdateGraph(profile,map =&gt; map.OwnedCollection(p =&gt; p.Functionalities));
  this.Repository.SaveChanges();  
  (...)  
  </code></pre>
  
  <p>Any ideas about it?<br>
  Thanks!</p>