protected function _relationshipDataIsNull($path)
    {
        $path = $this->_getPathObject($path);

        if ($this->_getProperty($path->dotted . '.data') === null) {
            return true;
        }

        return false;
    }
protected function _relationshipDataIsNull($path)
    {
        $path = $this->_getPathObject($path);

        if ($this->_getProperty($path->dotted . '.data') === null) {
            return true;
        }

        return false;
    }
protected function _relationshipDataIsNull ( $ path ) { $ path = $ this -> _getPathObject ( $ path ) ; if ( $ this -> _getProperty ( $ path -> dotted . '.data' ) === null ) { return true ; } return false ; }
Checks if relationship object has 'data' member set to null which is
allowed by the JSON API spec.

@param string|stdClass $path Dot separated path of relationship object or path object
@return bool
Checks if relationship object has data member set to null which is allowed by the JSON API spec .