src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Iterable<T> blockingMostRecent(T initialValue) {
        return new BlockingObservableMostRecent<T>(this, initialValue);
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Iterable<T> blockingMostRecent(T initialValue) {
        return new BlockingObservableMostRecent<T>(this, initialValue);
    }
Returns an {@link Iterable} that always returns the item most recently emitted by this
{@code Observable}.
<p>
<img width="640" height="426" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/blockingMostRecent.o.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code blockingMostRecent} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param initialValue
the initial value that the {@link Iterable} sequence will yield if this
{@code Observable} has not yet emitted an item
@return an {@link Iterable} that on each iteration returns the item that this {@code Observable}
has most recently emitted
@see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>