protected function getFieldOwnerKey(Field $field)
 {
     $ownerName = $field->getOwner()->getName();
     if (isset($this->formKeyCache[$ownerName])) {
         return $this->formKeyCache[$ownerName];
     }
     $name = $ownerName;
     if (ends_with($ownerName, '-form')) {
         $name = substr($ownerName, 0, strlen($ownerName) - 5);
     }
     $this->formKeyCache[$ownerName] = $name;
     return $this->formKeyCache[$ownerName];
 }