src/main/java/io/reactivex/Maybe.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Maybe<T> cache() {
        return RxJavaPlugins.onAssembly(new MaybeCache<T>(this));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Maybe<T> cache() {
        return RxJavaPlugins.onAssembly(new MaybeCache<T>(this));
    }
Returns a Maybe that subscribes to this Maybe lazily, caches its event
and replays it, to all the downstream subscribers.
<p>
<img width="640" height="410" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/cache.png" alt="">
<p>
The operator subscribes only when the first downstream subscriber subscribes and maintains
a single subscription towards this Maybe.
<p>
<em>Note:</em> You sacrifice the ability to dispose the origin when you use the {@code cache}.
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code cache} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@return a Maybe that, when first subscribed to, caches all of its items and notifications for the
benefit of subsequent subscribers
@see <a href="http://reactivex.io/documentation/operators/replay.html">ReactiveX operators documentation: Replay</a>