@HiveDecimalWritableVersionV1
  @Override
  public void write(DataOutput out) throws IOException {
    WritableUtils.writeVInt(out, scale);
    WritableUtils.writeVInt(out, internalStorage.length);
    out.write(internalStorage);
  }
Get a OldHiveDecimal instance from the writable and constraint it with maximum precision/scale.

@param maxPrecision maximum precision
@param maxScale maximum scale
@return OldHiveDecimal instance
storage-api/src/java/org/apache/hadoop/hive/serde2/io/HiveDecimalWritableV1.java