ScheduledTaskRegistrar's task list getters fail with NPE when no tasks set [SPR-13680] #18255
The ScheduledTaskRegistrar must be improved by adding few more helper methods.
The reason I am adding these helper methods as I tried accessing one of the getTriggerTaskList(), getCronTaskList(), getFixedRateTaskList(), getFixedDelayTaskList() which try to return a Collections.unmodifiableList list which does not accept a list object that is not instantiated (null) and throws a null pointer exception in case of null. This left me no other way to do null checks. Adding the helper methods would provide me if I should/shouldn't access it. There is already a helper method hasTasks but does not fit the solution to know if a specific TaskList is empty or null.