@Test
    public void requireThatIndexerForwardsDocumentsOfUnknownType() {
        var tester = new IndexingProcessorTester();
        Document input = new Document(new DocumentType("unknown"), "id:ns:unknown::");
        DocumentOperation output = tester.process(new DocumentPut(input));
        assertTrue(output instanceof DocumentPut);
        assertSame(input, ((DocumentPut)output).getDocument());
    }
@author Simon Thoresen Hult
@author bratseth
docprocs/src/test/java/com/yahoo/docprocs/indexing/IndexingProcessorTestCase.java