code: public static final Context enableOnDiscard(@Nullable Context target, Consumer<?> discardConsumer) {
  		Objects.requireNonNull(discardConsumer, "discardConsumer must be provided");
  		if (target == null) {
  			return Context.of(Hooks.KEY_ON_DISCARD, discardConsumer);
  		}
  		return target.put(Hooks.KEY_ON_DISCARD, discardConsumer);
  	}
docs: Utility method to activate the onDiscard feature (see {@link Flux#doOnDiscard(Class, Consumer)})
  in a target {@link Context}. Prefer using the {@link Flux} API, and reserve this for
  testing purposes.
  
  @param target the original {@link Context}
  @param discardConsumer the consumer that will be used to cleanup discarded elements
  @return a new {@link Context} that holds (potentially combined) cleanup {@link Consumer}