code: @SafeVarargs
      private <T extends Client> void writeHelper(Consumer<Client> consumer, T... clients) {
          var toExclude = Collections.newSetFromMap(new IdentityHashMap<>(clients.length));
          toExclude.addAll(List.of(clients));
          connectedClients.stream().filter(Predicate.not(toExclude::contains)).forEach(consumer);
      }
docs: A helper method that eliminates code duplication in the {@link #writeToAllExcept(Packet, Client[])} and
  {@link #writeAndFlushToAllExcept(Packet, Client[])} methods.
  
  @param <T> A {@link Client} or any of its children.
  @param consumer The action to perform for each {@link Client}.
  @param clients A variable amount of {@link Client}s to exclude from receiving the {@link Packet}.