title: CakePHP3 'contain' doesn't retrieve 'belongsTo'
body: <p>A user has multiple products. Each product has a brand.</p>
  <p>In the Products Table, I have a &quot;brand_id&quot; column.</p>
  <p>For the moment there is no join when I do <code>debug($user)</code>.</p>
  <p>I would like a join between Brands and Products Tables <code>(product.brand_id = brand.id)</code>. How can I solve this ?</p>
  <p>(sorry for my english)</p>
  <pre><code>//Controller Users
      $users = TableRegistry::getTableLocator()-&gt;get('users');
      $user = $users-&gt;find('all')
              -&gt;contain(['Products' =&gt; ['conditions' =&gt; ['id' =&gt; 25]]])
              -&gt;first();
      debug($user); 
  
  
  //Model Users
  public function initialize(array $config)
  {
      $this-&gt;hasMany('products');
  }
  
  
  //model Products
  public function initialize(array $config)
  {
      $this-&gt;belongsTo('brands');
  }
  </code></pre>