code: @Override
  	public MonetaryAmount apply(MonetaryAmount amount) {
  		Objects.requireNonNull(amount, "Amount required.");
  		return amount.multiply(percentValue);
  	}
docs: Gets the percentage of the amount.
  <p>
  This returns the monetary amount in percent. For example, for 10% 'EUR
  2.35' will return 0.235.
  <p>
  This is returned as a {@code MonetaryAmount}.
  
  @return the percent result of the amount, never {@code null}