@HiveDecimalWritableVersionV1
  public HiveDecimal getHiveDecimal() {
    if (!isSet) {
      return null;
    }
    HiveDecimal result = HiveDecimal.createFromFast(this);
    return result;
  }
Returns a HiveDecimal for the writable's current value.
<p>
Returns null if the writable isn't set.
storage-api/src/java/org/apache/hadoop/hive/serde2/io/HiveDecimalWritable.java