}

    /**
     * Defensive behavior: implementation throws NPE on null inputs by design.
     */
    @Test
    @DisplayName("implementation explicitly rejects nulls with NPE")
    void implementationRejectsNulls() {
        SmbFilenameFilter filter = (dir, name) -> {
            if (dir == null || name == null) {
                throw new NullPointerException("dir and name must be non-null");
            }