code: public PaymentSummaryBuilder addPriceLabel(String label, String amount) {
  		PriceLabel priceLabel = new PriceLabel(label, amount);
  		return addPriceLabel(priceLabel);
  	}
docs: Adds a {@link PriceLabel} to the {@link PaymentSummary}.
  
  @param label
  the {@link PriceLabel#label}.
  @param amount
  the {@link PriceLabel#amount}.
  @return this builder.