code: public OperationFuture<List<Server>> modify(List<Server> serverList, ModifyServerConfig modifyServerConfig) {
          List<JobFuture> futures = serverList.stream()
              .map(
                  server ->
                      modify(server, modifyServerConfig).jobFuture()
              )
              .collect(toList());
  
          return new OperationFuture<>(
              serverList,
              new ParallelJobsFuture(futures)
          );
      }
docs: Modify list of servers
  @param serverList server list
  @param modifyServerConfig server config
  @return OperationFuture wrapper for list of Servers