@Test
    public void testFunnyDocName() {
        com.yahoo.vespa.documentgen.test.Class c = new com.yahoo.vespa.documentgen.test.Class(new DocumentId("id:class:class::0"));
        c.setClassf("foo");
    }
Packs the given doc to Book
@param d doc, never null
@return a Book object or null if input doc isn't a Book
documentgen-test/src/test/java/com/yahoo/vespa/config/DocumentGenPluginTest.java