code: public boolean isScheduled(ScheduledTrigger scheduledTrigger) throws SchedulerException {
          try {
              return scheduler.isScheduled(scheduledTrigger.getId(), Scheduler.DEFAULT_GROUP);
          } catch (org.quartz.SchedulerException e) {
              throw new SchedulerException("Exception occurred while checking isScheduled() for: " + scheduledTrigger, e);
          }
      }
docs: Checks if a {@code ScheduledTrigger} is scheduled in the scheduler or not.
  @warn exception SchedulerException description missing
  @warn parameter scheduledTrigger description missing
  
  @param scheduledTrigger
  @return
  @throws SchedulerException