code: @Deprecated
      public Transaction enterOfflinePayment(final Integer invoiceId, final Transaction payment) {
          return enterOfflinePayment(invoiceId.toString(), payment);
      }
docs: Enter an offline payment for a manual invoice (beta) - Recurly Enterprise Feature
  
  @deprecated Prefer using Invoice#getId() as the id param (which is a String)
  
  @param invoiceId Recurly Invoice ID
  @param payment   The external payment