add Zone option to Dependency Form

application/forms/IcingaDependencyForm.php

@@ -31,9 +31,30 @@ class IcingaDependencyForm extends DirectorObjectForm
              ->addAssignmentElements()
              ->addEventFilterElements(['states'])
              ->groupMainProperties()
+             ->addZoneSection()
              ->setButtons();
     }
 
+    protected function addZoneSection()
+    {
+        $this->addZoneElement(true);
+
+        $elements = array(
+            'zone_id',
+        );
+        $this->addDisplayGroup($elements, 'clustering', array(
+            'decorators' => array(
+                'FormElements',
+                array('HtmlTag', array('tag' => 'dl')),
+                'Fieldset',
+            ),
+            'order' => 80,
+            'legend' => $this->translate('Zone settings')
+        ));
+
+        return $this;
+    }
+
     protected function addNameElement()
     {
         $this->addElement('text', 'object_name', [