code: public void startTrigger(final FlowTrigger flowTrigger, final String flowId,
        final int flowVersion, final String submitUser, final Project project) {
      final TriggerInstance triggerInst = createTriggerInstance(flowTrigger, flowId, flowVersion,
          submitUser, project);
      this.flowTriggerExecutorService.submit(() -> {
        logger.info("Starting the flow trigger [trigger instance id: {}] by {}",
            triggerInst.getId(), submitUser);
        start(triggerInst);
      });
    }
docs: Start the trigger. The method will be scheduled to invoke by azkaban scheduler.