function findFieldByKey(string $key)
    {
        $this->checkFormIsBuilt();

        $fields = collect($this->fields);

        if(strpos($key, ".") !== false) {
            list($key, $itemKey) = explode(".", $key);
            $listField = $fields->where("key", $key)->first();

            return $listField->findItemFormFieldByKey($itemKey);
        }

        return $fields->where("key", $key)->first();
    }