@Override
    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "IT_NO_SUCH_ELEMENT",
        justification = "Intentional")
    public Tag next() {
      return null;
    }
Iterator returned when no Tags. Used by CellUtil too.
hbase-common/src/main/java/org/apache/hadoop/hbase/TagUtil.java