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

        config.getMetadataFilter().filter(metadata);

        assertEquals(1, metadata.size());
        assertEquals("content", metadata.get("content"));
    }