* @return True if the password was successfully changed in all chains, false otherwise.
     */
    public boolean changePassword(final String username, final String password) {
        return chains().get(stream -> stream.allMatch(c -> c.changePassword(username, password)));
    }

    /**
     * Deletes a user from all authentication chains.
     * @param user The user to delete.
     */
    public void delete(final User user) {

     */
    protected boolean isEmptyArray(final String[] values) {
        if (values == null || values.length == 0) {
            return true;
        }
        return stream(values).get(stream -> stream.allMatch(StringUtil::isBlank));
    }

    /**
     * Simplifies the array.
     *
     * @param values The array.
     * @return The simplified array.
     */