code: public String schedule(Trigger trigger, Runnable task) {
          ScheduledFuture<?> future = getCurrentScheduler().schedule(task, trigger);
          String id = Schedulers.getUUID();
          runningSchedullers.put(id, future);
          Schedulers.increaseNoOfRunningSchedullers();
          setCurrentScheduler(null);
          return id;
      }
docs: Schedule.
  
  @param trigger the trigger
  @param task the task
  @return the string