private final Object messagesLock = new Object();

    /**
     * Default constructor.
     */
    public ChatSession() {
        this.sessionId = UUID.randomUUID().toString();
        this.createdAt = LocalDateTime.now();
        this.lastAccessedAt = this.createdAt;
        this.messages = new CopyOnWriteArrayList<>();
    }

    /**
     * Creates a new chat session for the specified user.
     *

  public Collection<V> get(@ParametricNullness K key) {
    if (keyPredicate.apply(key)) {
      return unfiltered.get(key);
    } else if (unfiltered instanceof SetMultimap) {
      return new AddRejectingSet<>(key);
    } else {
      return new AddRejectingList<>(key);
    }
  }

  private static final class AddRejectingSet<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingSet<V> {

  public Collection<V> get(@ParametricNullness K key) {
    if (keyPredicate.apply(key)) {
      return unfiltered.get(key);
    } else if (unfiltered instanceof SetMultimap) {
      return new AddRejectingSet<>(key);
    } else {
      return new AddRejectingList<>(key);
    }
  }

  private static final class AddRejectingSet<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingSet<V> {

        saveToken();
        return asHtml(path_AdminPlugin_AdminPluginInstallpluginJsp).renderWith(data -> {
            final List<Map<String, String>> result = new ArrayList<>();
            final Map<String, String> map = new HashMap<>();
            map.put("id", UPLOAD);
            map.put("name", "");
            map.put("version", "");
            result.add(map);
            try {

  }

  @Override
  Iterator<E> elementIterator() {
    return new Itr<E>() {
      @Override
      E output(int index) {
        return enumConstants[index];
      }
    };
  }

  @Override
  Iterator<Entry<E>> entryIterator() {
    return new Itr<Entry<E>>() {
      @Override
      Entry<E> output(int index) {
        return new Multisets.AbstractEntry<E>() {
          @Override

        return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
      } else if (collection instanceof SortedSet) {
        return new WrappedSortedSet(key, (SortedSet<V>) collection, null);
      } else if (collection instanceof Set) {
        return new WrappedSet(key, (Set<V>) collection);
      } else {
        return new WrappedCollection(key, collection, null);
      }
    }

        return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
      } else if (collection instanceof SortedSet) {
        return new WrappedSortedSet(key, (SortedSet<V>) collection, null);
      } else if (collection instanceof Set) {
        return new WrappedSet(key, (Set<V>) collection);
      } else {
        return new WrappedCollection(key, collection, null);
      }
    }

      if (index == null) {
        throw new IllegalArgumentException(
            getKeyRole() + " " + key + " not in " + keyIndex.keySet());
      }
      return setValue(index, value);
    }

    @Override
    public @Nullable V remove(@Nullable Object key) {
      throw new UnsupportedOperationException();
    }

    @Override
    public void clear() {
      throw new UnsupportedOperationException();
    }

        return new TreeSet<E>(contents);
      }
    },
    UnmodifiableSetImpl {
      @Override
      public <E extends Comparable<E>> Set<E> create(Collection<E> contents) {
        return unmodifiableSet(new HashSet<E>(contents));
      }
    },
    SynchronizedSetImpl {
      @Override
      public <E extends Comparable<E>> Set<E> create(Collection<E> contents) {
        return synchronizedSet(new HashSet<E>(contents));

  public static Joiner on(String separator) {
    return new Joiner(separator);
  }

  /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
  public static Joiner on(char separator) {
    return new Joiner(String.valueOf(separator));
  }

  private final String separator;

  private Joiner(String separator) {