code: public InvoiceData getInvoice(Calendar calendar, String pricingAccountAlias) {
          return getInvoice(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH) + 1, pricingAccountAlias);
      }
docs: Gets a list of invoicing data for a given account alias for a given month.
  @param calendar Date of usage
  @param pricingAccountAlias Short code of the account that sends the invoice for the accountAlias
  @return the invoice data