title: Entity with many to many not loading collection property
body: <p>I have an entity Roster that has a collection of players.  </p>
  
  <pre><code>public class Roster
  {
      public Roster()
      {
          Players = new List&lt;Player&gt;();
      }
  
      public int RosterId { get; set; }
  
      [MaxLength(100)]
      [Required]
      public string RosterName { get; set; }
  
      public ICollection&lt;Player&gt; Players { get; set; }
  }
  public class Player
  {
      public int PlayerId { get; set; }
      [MaxLength(100)]
      [Required]
      public string PlayerName { get; set; }
      public virtual ICollection&lt;Roster&gt; Rosters { get; set; }
  }
  </code></pre>
  
  <p>I have defined the relationship using the fluent api</p>
  
  <pre><code>// many to many Roster - Players
  modelBuilder.Entity&lt;Roster&gt;()
  .HasMany(t =&gt; t.Players)
  .WithMany(t=&gt;t.Rosters)
  .Map(m =&gt;
  {
      m.ToTable("RosterPlayers");
      m.MapLeftKey("RosterId");
      m.MapRightKey("PlayerId");
  });
  </code></pre>
  
  <p>I can save a player to a roster like this</p>
  
  <pre><code>var roster = rosterRepository.GetById(rosterId);
  var player = playerRepository.GetById(playerId);
  
  roster.Players.Add(player);
  rosterRepository.Update(roster);
  ...
  </code></pre>
  
  <p>However, when I retrieve the roster, the players collection is not loaded.  I verified the data exists with all the proper values and the following sql does yeild data.</p>
  
  <pre><code>SELECT * from Rosters r 
  INNER JOIN RosterPlayers rp on r.RosterId = rp.RosterId
  INNER JOIN Players p ON p.PlayerId = rp.PlayerId
  </code></pre>
  
  <p>What am I missing?</p>