private static List<TransportRequest> consumeTransportRequests(String action) {
   List<TransportRequest> requests = new ArrayList<>();
   Iterable<TransportService> transportServices =
       internalCluster().getInstances(TransportService.class);
   for (TransportService transportService : transportServices) {
     List<TransportRequest> transportRequests =
         ((InterceptingTransportService) transportService).consumeRequests(action);
     if (transportRequests != null) {
       requests.addAll(transportRequests);
     }
   }
   return requests;
 }