@Override
    public <T> boolean schedule(
        SchedulableInstance<T> schedulableInstance, ScheduleOptions whenExists) {
      return schedule(
          schedulableInstance.getTaskInstance(),
          schedulableInstance.getNextExecutionTime(clock.now()),
          whenExists);
    }
Will cause getScheduledExecutions(..) to return executions in priority order.
db-scheduler/src/main/java/com/github/kagkarlsson/scheduler/SchedulerClient.java