docs: public static boolean isCharge(final InvoiceItem invoiceItem) {
          return InvoiceItemType.TAX.equals(invoiceItem.getInvoiceItemType()) ||
                 InvoiceItemType.EXTERNAL_CHARGE.equals(invoiceItem.getInvoiceItemType()) ||
                 InvoiceItemType.FIXED.equals(invoiceItem.getInvoiceItemType()) ||
                 InvoiceItemType.USAGE.equals(invoiceItem.getInvoiceItemType()) ||
                 InvoiceItemType.RECURRING.equals(invoiceItem.getInvoiceItemType());
      }