public static function getNonEmptyValuesAsString(array $values, $separator = ', ')
    {
        /*
         * No elements?
         * Nothing to do
         */
        if (empty($values)) {
            return null;
        }

        $nonEmpty = self::getNonEmptyValues($values);

        /*
         * No values?
         * Nothing to do
         */
        if (empty($nonEmpty)) {
            return '';
        }

        return implode($separator, $nonEmpty);
    }