code: public static Set<Integer> worker_output_tasks(WorkerData workerData) {
          ContextMaker context_maker = workerData.getContextMaker();
          Set<Integer> taskIds = workerData.getTaskIds();
          StormTopology topology = workerData.getSysTopology();
  
          Set<Integer> rtn = new HashSet<>();
  
          for (Integer taskId : taskIds) {
              TopologyContext context = context_maker.makeTopologyContext(topology, taskId, null);
  
              // <StreamId, <ComponentId, Grouping>>
              Map<String, Map<String, Grouping>> targets = context.getThisTargets();
              for (Map<String, Grouping> e : targets.values()) {
                  for (String componentId : e.keySet()) {
                      List<Integer> tasks = context.getComponentTasks(componentId);
                      rtn.addAll(tasks);
                  }
              }
          }
  
          return rtn;
      }
docs: get current task's output task list