src/main/java/io/reactivex/Completable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Completable repeatUntil(BooleanSupplier stop) {
        return fromPublisher(toFlowable().repeatUntil(stop));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Completable repeatUntil(BooleanSupplier stop) {
        return fromPublisher(toFlowable().repeatUntil(stop));
    }
Returns a Completable that repeatedly subscribes to this Completable so long as the given
stop supplier returns false.
<p>
<img width="640" height="381" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Completable.repeatUntil.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code repeatUntil} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>
@param stop the supplier that should return true to stop resubscribing.
@return the new Completable instance
@throws NullPointerException if stop is null