@HiveDecimalWritableVersionV2
  public boolean isSet() {
    return isSet;
  }
Does this writable have a current value?
<p>
A return of false means a current value wasn't set, or an operation like mutateAdd overflowed,
or a set* method couldn't convert the input value, etc.
storage-api/src/java/org/apache/hadoop/hive/serde2/io/HiveDecimalWritable.java