Fix visibility

src/View/JsonView.php

@@ -79,7 +79,7 @@ class JsonView extends SerializedView
      *
      * @var string
      */
-    public $_responseType = 'json';
+    protected $_responseType = 'json';
 
     /**
      * List of special view vars.

src/View/SerializedView.php

@@ -28,7 +28,7 @@ class SerializedView extends View
      *
      * @var string
      */
-    public $_responseType;
+    protected $_responseType;
 
     /**
      * Constructor

src/View/XmlView.php

@@ -78,7 +78,7 @@ class XmlView extends SerializedView
      *
      * @var string
      */
-    public $_responseType = 'xml';
+    protected $_responseType = 'xml';
 
     /**
      * List of special view vars.