private @Nullable Map<String, String> getExtraMap(
        ProducerListener2 listener, ProducerContext producerContext, Postprocessor postprocessor) {
      if (!listener.requiresExtraMap(producerContext, NAME)) {
        return null;
      }
      return ImmutableMap.of(POSTPROCESSOR, postprocessor.getName());
    }
Performs postprocessing and takes care of scheduling.
imagepipeline/src/main/java/com/facebook/imagepipeline/producers/PostprocessorProducer.java