public String getAlbumArtist() {
        for (ID3Tags tag : tags) {
            if (tag.getAlbumArtist() != null) {
                return tag.getAlbumArtist();
            }
        }
        return null;
    }
Takes an array of {@link ID3Tags} in preference order, and when asked for
a given tag, will return it from the first {@link ID3Tags} that has it.
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-audiovideo-module/src/main/java/org/apache/tika/parser/mp3/CompositeTagHandler.java