code: public final <K> Mono<Map<K, T>> collectMap(Function<? super T, ? extends K> keyExtractor) {
  		return collectMap(keyExtractor, identityFunction());
  	}
docs: Collect all elements emitted by this {@link Flux} into a hashed {@link Map} that is
  emitted by the resulting {@link Mono} when this sequence completes.
  The key is extracted from each element by applying the {@code keyExtractor}
  {@link Function}. In case several elements map to the same key, the associated value
  will be the most recently emitted element.
  
  <p>
  <img class="marble" src="doc-files/marbles/collectMapWithKeyExtractor.svg" alt="">
  
  @reactor.discard This operator discards the buffer upon cancellation or error triggered by a data signal.
  
  @param keyExtractor a {@link Function} to map elements to a key for the {@link Map}
  @param <K> the type of the key extracted from each source element
  
  @return a {@link Mono} of a {@link Map} of key-element pairs (only including latest
  element in case of key conflicts)