public Path getInputRoot(String subdir) throws Exception {
        String path = (subdir == null || subdir.isEmpty()) ? "/test-input" : "/test-input/" + subdir;
        return Paths.get(getResourceAsUri(path));
    }
helper method equivalent to File#listFiles()
grabs children only, does not walk recursively

@param p
@return
tika-batch/src/test/java/org/apache/tika/batch/fs/FSBatchTestBase.java