code: @Override
      public int compareTo(MonetaryAmount o) {
          Objects.requireNonNull(o);
          int compare = getCurrency().getCurrencyCode().compareTo(o.getCurrency().getCurrencyCode());
          if (compare == 0) {
              compare = this.number.compareTo(Money.from(o).number);
          }
          return compare;
      }
docs: /*
  @see java.lang.Comparable#compareTo(java.lang.Object)