src/main/java/io/reactivex/Maybe.java
@BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
    @CheckReturnValue
    @NonNull
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U> Maybe<T> delaySubscription(Publisher<U> subscriptionIndicator) {
        ObjectHelper.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
        return RxJavaPlugins.onAssembly(new MaybeDelaySubscriptionOtherPublisher<T, U>(this, subscriptionIndicator));
    }
@BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
    @CheckReturnValue
    @NonNull
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U> Maybe<T> delaySubscription(Publisher<U> subscriptionIndicator) {
        ObjectHelper.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
        return RxJavaPlugins.onAssembly(new MaybeDelaySubscriptionOtherPublisher<T, U>(this, subscriptionIndicator));
    }
Returns a Maybe that delays the subscription to this Maybe
until the other Publisher emits an element or completes normally.
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The {@code Publisher} source is consumed in an unbounded fashion (without applying backpressure).</dd>
<dt><b>Scheduler:</b></dt>
<dd>This method does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param <U> the value type of the other Publisher, irrelevant
@param subscriptionIndicator the other Publisher that should trigger the subscription
to this Publisher.
@return a Maybe that delays the subscription to this Maybe
until the other Publisher emits an element or completes normally.