code: public final <V, C extends Collection<? super V>> Flux<T> distinct(
  			Function<? super T, ? extends V> keySelector,
  			Supplier<C> distinctCollectionSupplier) {
  		return this.distinct(keySelector, distinctCollectionSupplier, Collection::add, Collection::clear);
  	}
docs: For each {@link Subscriber}, track elements from this {@link Flux} that have been
  seen and filter out duplicates, as compared by a key extracted through the user
  provided {@link Function} and by the {@link Collection#add(Object) add method}
  of the {@link Collection} supplied (typically a {@link Set}).
  
  <p>
  <img class="marble" src="doc-files/marbles/distinctWithKey.svg" alt="">
  
  @reactor.discard This operator discards elements that don't match the distinct predicate,
  but you should use the version with a cleanup if you need discarding of keys
  categorized by the operator as "seen". See {@link #distinct(Function, Supplier, BiPredicate, Consumer)}.
  
  @param keySelector function to compute comparison key for each element
  @param distinctCollectionSupplier supplier of the {@link Collection} used for distinct
  check through {@link Collection#add(Object) add} of the key.
  
  @param <V> the type of the key extracted from each value in this sequence
  @param <C> the type of Collection used for distinct checking of keys
  
  @return a filtering {@link Flux} only emitting values with distinct keys