public function getField($groupKey, $fieldKey)
    {
        foreach ($this->parts as $part) {
            if ($part->getKey() !== $groupKey) {
                continue;
            }
            
            foreach ($part->getParts() as $field) {
                if ($field->getKey() !== $fieldKey) {
                    continue;
                }
                
                return $field;
            }
        }
        
        return false;
    }