public abstract void filter(Metadata metadata) throws TikaException;
@Test
    public void testMimeClearingFilterConfig() throws Exception {
        TikaConfig config = getConfig("TIKA-3137-mimes-uc.xml");

        Metadata metadata = new Metadata();
        metadata.set(Metadata.CONTENT_TYPE, MediaType.image("jpeg").toString());
        metadata.set("author", "author");

        MetadataFilter filter = config.getMetadataFilter();
        filter.filter(metadata);
        assertEquals(0, metadata.size());

        metadata.set(Metadata.CONTENT_TYPE, MediaType.text("plain").toString());
        metadata.set("author", "author");
        filter.filter(metadata);
        assertEquals(2, metadata.size());
        assertEquals("AUTHOR", metadata.get("author"));
    }