@Override
  public void produceResults(Consumer<EncodedImage> consumer, ProducerContext context) {
    OnFirstImageConsumer onFirstImageConsumer = new OnFirstImageConsumer(consumer, context);
    mInputProducer1.produceResults(onFirstImageConsumer, context);
  }
Producer that coordinates fetching two separate images.

<p>The first producer is kicked off, and once it has returned all its results, the second
producer is kicked off if necessary.
imagepipeline/src/main/java/com/facebook/imagepipeline/producers/BranchOnSeparateImagesProducer.java