@Override
        public void handle(String filename, MediaType mediaType, InputStream stream) {
            if (skipTypes.contains(mediaType)) {
                return;
            }
            mediaTypes.add(mediaType);
            filenames.add(filename);
        }
Keeps track of media types and file names recursively.
tika-core/src/test/java/org/apache/tika/TikaTest.java