public function getValuesByTag(string $tag): array
    {
        $result = array();

        foreach ($this->_definition as $key => $value) {
            $tags = $this->getFieldProperty($key, 'tags');

            if (is_array($tags) && in_array($tag, $tags)) {
                $result[$key] = $this->$key;
            }
        }

        return $result;
    }