public boolean isZero() {
    assert ((this.signum == 0 && this.unscaledValue.isZero()) || (this.signum != 0 && !this.unscaledValue
        .isZero()));
    return this.signum == 0;
  }
@return whether this value represents zero.
common/src/java/org/apache/hadoop/hive/common/type/Decimal128.java