@NonNull
    public Set<Job> getAllJobsForTag(@NonNull String tag) {
        return mJobExecutor.getAllJobsForTag(tag);
    }
@ NonNull public Set < Job > getAllJobsForTag ( @ NonNull String tag ) { return mJobExecutor . getAllJobsForTag ( tag ) ; }
Jobs are cached in memory even if they already have finished. But finished jobs are never
restored after the app has relaunched. Since finished jobs could cause memory leaks, they wrapped
inside of a {@link WeakReference} and can be removed from memory. If you need to know the results
of finished jobs or whether a job has been run, you can call {@link #getAllJobResults()}.

@param tag The tag of the running or finished jobs.
@return A duplicate {@link Set} containing all running and cached finished jobs associated with
this tag or an empty set. Never returns {@code null}. The set may be modified without direct
effects to the actual backing store.