src/main/java/io/reactivex/Flowable.java
@SuppressWarnings({ "unchecked", "rawtypes" })
    @CheckReturnValue
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? extends T>> sources) {
        return fromIterable(sources).flatMap((Function)Functions.identity(), true);
    }
@SuppressWarnings({ "unchecked", "rawtypes" })
    @CheckReturnValue
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <T> Flowable<T> mergeDelayError(Iterable<? extends Publisher<? extends T>> sources) {
        return fromIterable(sources).flatMap((Function)Functions.identity(), true);
    }
Flattens an Iterable of Publishers into one Publisher, in a way that allows a Subscriber to receive all
successfully emitted items from each of the source Publishers without being interrupted by an error
notification from one of them.
<p>
This behaves like {@link #merge(Publisher)} except that if any of the merged Publishers notify of an
error via {@link Subscriber#onError onError}, {@code mergeDelayError} will refrain from propagating that
error notification until all of the merged Publishers have finished emitting items.
<p>
<img width="640" height="380" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/mergeDelayError.png" alt="">
<p>
Even if multiple merged Publishers send {@code onError} notifications, {@code mergeDelayError} will only
invoke the {@code onError} method of its Subscribers once.
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The operator honors backpressure from downstream. All inner {@code Publisher}s are expected to honor
backpressure; if violated, the operator <em>may</em> signal {@code MissingBackpressureException}.</dd>
<dt><b>Scheduler:</b></dt>
<dd>{@code mergeDelayError} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param <T> the common element base type
@param sources
the Iterable of Publishers
@return a Flowable that emits items that are the result of flattening the items emitted by the
Publishers in the Iterable
@see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>