src/main/java/io/reactivex/Flowable.java
@CheckReturnValue
    @NonNull
    @BackpressureSupport(BackpressureKind.ERROR)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U> Flowable<T> debounce(Function<? super T, ? extends Publisher<U>> debounceIndicator) {
        ObjectHelper.requireNonNull(debounceIndicator, "debounceIndicator is null");
        return RxJavaPlugins.onAssembly(new FlowableDebounce<T, U>(this, debounceIndicator));
    }
@CheckReturnValue
    @NonNull
    @BackpressureSupport(BackpressureKind.ERROR)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U> Flowable<T> debounce(Function<? super T, ? extends Publisher<U>> debounceIndicator) {
        ObjectHelper.requireNonNull(debounceIndicator, "debounceIndicator is null");
        return RxJavaPlugins.onAssembly(new FlowableDebounce<T, U>(this, debounceIndicator));
    }
Returns a Flowable that mirrors the source Publisher, except that it drops items emitted by the
source Publisher that are followed by another item within a computed debounce duration.
<p>
<img width="640" height="425" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/debounce.f.png" alt="">
<p>
The delivery of the item happens on the thread of the first {@code onNext} or {@code onComplete}
signal of the generated {@code Publisher} sequence,
which if takes too long, a newer item may arrive from the upstream, causing the
generated sequence to get cancelled, which may also interrupt any downstream blocking operation
(yielding an {@code InterruptedException}). It is recommended processing items
that may take long time to be moved to another thread via {@link #observeOn} applied after
{@code debounce} itself.
<dl>
<dt><b>Backpressure:</b></dt>
<dd>This operator does not support backpressure as it uses the {@code debounceSelector} to mark
boundaries.</dd>
<dt><b>Scheduler:</b></dt>
<dd>This version of {@code debounce} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param <U>
the debounce value type (ignored)
@param debounceIndicator
function to retrieve a sequence that indicates the throttle duration for each item
@return a Flowable that omits items emitted by the source Publisher that are followed by another item
within a computed debounce duration
@see <a href="http://reactivex.io/documentation/operators/debounce.html">ReactiveX operators documentation: Debounce</a>
@see <a href="https://github.com/ReactiveX/RxJava/wiki/Backpressure">RxJava wiki: Backpressure</a>