}

        @Test
        void unwrapDOSFilter_returnsInnerDosFileFilter_whenWrapped() throws Exception {
            // Arrange: create a ResourceFilterWrapper that wraps a DosFileFilter
            DosFileFilter dos = new DosFileFilter("abc", 7);
            Object wrapper = newPrivateInner("ResourceFilterWrapper", new Class<?>[] { SmbFileFilter.class }, dos);

        }
    }

    private static DosFileFilter unwrapDOSFilter(final ResourceFilter ff) {
        if (ff instanceof ResourceFilterWrapper) {
            final SmbFileFilter sff = ((ResourceFilterWrapper) ff).getFileFilter();
            if (sff instanceof DosFileFilter) {
                return (DosFileFilter) sff;
            }
        }
        return null;
    }