Merge branch 'whitecube:master' into collapsed_preview

Author: fedeisas

src/Layouts/Layout.php

@@ -110,6 +110,20 @@ class Layout implements LayoutInterface, JsonSerializable, ArrayAccess, Arrayabl
      */
     protected $wasRecentlyCreated = false;
 
+    /**
+     * The relation resolver callbacks for the Layout.
+     *
+     * @var array
+     */
+    protected  $relationResolvers = [];
+
+    /**
+     * The loaded relationships for the Layout.
+     *
+     * @var array
+     */
+    protected $relations = [];
+
     /**
      * Create a new base Layout instance
      *
@@ -626,6 +640,20 @@ protected function relationLoaded()
         return false;
     }
 
+    /**
+     * Get the dynamic relation resolver if defined or inherited, or return null.
+     * Since it is not possible to define a relation on a layout, this method
+     * returns null
+     *
+     * @param  string  $class
+     * @param  string  $key
+     * @return mixed
+     */
+    public function relationResolver($class, $key)
+    {
+        return null;
+    }
+
     /**
      * Transform layout for serialization
      *