code: public OperationFuture<List<Server>> reboot(Server... serverRefs) {
          return powerOperationResponse(
              Arrays.asList(serverRefs),
              "Reboot",
              client.reboot(ids(serverRefs))
          );
      }
docs: Reboot a single server or group of servers
  
  @param serverRefs server references list
  @return OperationFuture wrapper for Server list