code: public MoneyFormatterBuilder appendAmount(MoneyAmountStyle style) {
          MoneyFormatter.checkNotNull(style, "MoneyAmountStyle must not be null");
          AmountPrinterParser pp = new AmountPrinterParser(style);
          return appendInternal(pp, pp);
      }
docs: Appends the amount to the builder using the specified amount style.
  <p>
  The amount is the value itself, such as '12.34'.
  <p>
  The amount style allows the formatting of the number to be controlled in detail.
  This includes the characters for positive, negative, decimal, grouping and whether
  to output the absolute or signed amount.
  See {@link MoneyAmountStyle} for more details.
  
  @param style  the style to use, not null
  @return this, for chaining, never null