title: Doctrine MongoDb Embedded Document - How to specify fields
body: <p>I'm using Symfony 2 with Doctrine MongoDb bundle. </p>
  
  <p>There are two classes with mappings:</p>
  
  <pre><code>/**
   * @MongoDB\Document
   */
  class Consultant
  {
      /**
       * @MongoDB\Id(strategy="NONE")
       */
      protected $id;
  
      /**
       * @MongoDB\EmbedMany(targetDocument="Specialization", strategy="set")
       */
      protected $specs;
  }
  
  /**
   * @MongoDB\Document
   */
  class Specialization
  {
      /**
       * @MongoDB\Id
       */
      protected $id;
  
      /**
       * @MongoDB\String
       */
      protected $name;
  
      /**
       * @MongoDB\Boolean
       */
      protected $visible = true;
  }
  </code></pre>
  
  <p>After saving a consultant, the Mongo record looks like this:</p>
  
  <pre><code>{
     "_id": "1",
     "name": "Manager",
     "specs": {
       "0": {
         "_id": ObjectId("50d071ac6146a1f342000001"),
         "name": "Support",
         "visible": false 
      },
       "1": {
         "_id": ObjectId("50d069336146a10244000000"),
         "name": "Orders",
         "visible": false 
      } 
    } 
  }
  </code></pre>
  
  <p>Everything is fine except the redundant field 'visible'. </p>
  
  <p>Is there a way to specify what fields should be embedded by Doctrine using <code>@EmbedMany</code> annotation?</p>