@NonNull
    public Flowable<Changes> observeChangesOfTag(@NonNull String tag, @NonNull BackpressureStrategy backpressureStrategy) {
        checkNotEmpty(tag, "Tag can not be null or empty");
        return observeChangesOfTags(Collections.singleton(tag), backpressureStrategy);
    }
@ NonNull public Flowable < Changes > observeChangesOfTag ( @ NonNull String tag , @ NonNull BackpressureStrategy backpressureStrategy ) { checkNotEmpty ( tag , "Tag can not be null or empty" ) ; return observeChangesOfTags ( Collections . singleton ( tag ) , backpressureStrategy ) ; }
Allows observer changes of required tag.
<p/>
Tags are optional meta information that you can attach to Changes object
to have more fine-grained control over observing changes in the database.
<p/>
Notice that {@link StorIOSQLite} knows only about changes
that happened as a result of Put or Delete Operations executed
on this instance of {@link StorIOSQLite}.
<p/>
Emission may happen on any thread that performed Put or Delete operation,
so it's recommended to apply {@link Flowable#observeOn(io.reactivex.Scheduler)}
if you need to receive events on a special thread.
<p/>
Notice, that returned {@link Flowable} is "Hot Flowable", it never ends, which means,
that you should manually dispose from it to prevent memory leak.
Also, it can cause BackPressure problems.

@param tag tag to monitor.
@return {@link io.reactivex.Flowable} of {@link Changes} subscribed to changes of required tag.