public abstract void filter(Metadata metadata) throws TikaException;
@Test
    public void testConfigIncludeFilter() throws Exception {
        TikaConfig config = getConfig("TIKA-3137-include.xml");
        Metadata metadata = new Metadata();
        metadata.set("title", "title");
        metadata.set("author", "author");
        metadata.set("content", "content");

        config.getMetadataFilter().filter(metadata);

        assertEquals(2, metadata.size());
        assertEquals("title", metadata.get("title"));
        assertEquals("author", metadata.get("author"));
    }