private Music getMusicBasic() {
        Music music = new Music(new DocumentId("id:music:music::0"));
        music.setArtist("Astroburger");
        music.setDisp_song("disp");
        music.setSong("Calling the sun");
        music.setYear(2005);
        music.setUri("http://astro.burger");
        music.setWeight_src(10.654f);
        music.setEitheror(false);
        return music;
    }
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