public byte getTag(Object o) {
    if (o == null) {
      return -1;
    }
    LazyBinaryUnion lazyBinaryUnion = (LazyBinaryUnion) o;
    return lazyBinaryUnion.getTag();
  }
Return the tag of the object.
serde/src/java/org/apache/hadoop/hive/serde2/lazybinary/objectinspector/LazyBinaryUnionObjectInspector.java