code: @Override
      public double doubleValueExact() {
          double d = this.number.doubleValue();
          if (d == Double.NEGATIVE_INFINITY || d == Double.POSITIVE_INFINITY) {
              throw new ArithmeticException("Unable to convert to double: "
                      + this.number);
          }
          return d;
      }
docs: /*
  (non-Javadoc)
  @see javax.money.NumberValue#getDoubleValueExact()