src/main/java/io/reactivex/Flowable.java
@BackpressureSupport(BackpressureKind.SPECIAL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final void blockingSubscribe(Subscriber<? super T> subscriber) {
        FlowableBlockingSubscribe.subscribe(this, subscriber);
    }
@BackpressureSupport(BackpressureKind.SPECIAL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final void blockingSubscribe(Subscriber<? super T> subscriber) {
        FlowableBlockingSubscribe.subscribe(this, subscriber);
    }
Subscribes to the source and calls the {@link Subscriber} methods <strong>on the current thread</strong>.
<p>
Note that calling this method will block the caller thread until the upstream terminates
normally, with an error or the {@code Subscriber} cancels the {@link Subscription} it receives via
{@link Subscriber#onSubscribe(Subscription)}.
Therefore, calling this method from special threads such as the
Android Main Thread or the Swing Event Dispatch Thread is not recommended.
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The supplied {@code Subscriber} determines how backpressure is applied.</dd>
<dt><b>Scheduler:</b></dt>
<dd>{@code blockingSubscribe} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>
The cancellation and backpressure is composed through.
@param subscriber the subscriber to forward events and calls to in the current thread
@since 2.0