protected function getWsdlElementAttributes($comment)
    {
        $nillable = $minOccurs = $maxOccurs = null;
        if (preg_match('/{(.+)}/', $comment, $attr)) {
            if (preg_match_all('/((\w+)\s*=\s*(\w+))/mi', $attr[1], $attr)) {
                foreach ($attr[2] as $id => $prop) {
                    $prop = strtolower($prop);
                    $val = strtolower($attr[3][$id]);
                    if ($prop == 'nillable') {
                        if ($val == 'false' || $val == 'true') {
                            $nillable = $val;
                        } else {
                            $nillable = $val ? 'true' : 'false';
                        }
                    } elseif ($prop == 'minoccurs') {
                        $minOccurs = intval($val);
                    } elseif ($prop == 'maxoccurs') {
                        $maxOccurs = ($val == 'unbounded') ? 'unbounded' : intval($val);
                    }
                }
            }
        }
        return [
            'nillable' => $nillable,
            'minOccurs' => $minOccurs,
            'maxOccurs' => $maxOccurs
        ];
    }