code: OperationFuture<List<Server>> restore(List<Server> serverList, String groupId) {
          List<JobFuture> futures = serverList.stream()
              .map(server ->
                  baseServerResponse(
                      client.restore(
                          idByRef(server),
                          new RestoreServerRequest()
                              .targetGroupId(groupId))
                  )
                  .jobFuture()
              )
              .collect(toList());
  
          return new OperationFuture<>(
              serverList,
              new ParallelJobsFuture(futures)
          );
      }
docs: Restore a list of archived servers to a specified group
  @param serverList server List references
  @return OperationFuture wrapper for list of ServerRef