@Override public boolean addAll(Collection<? extends E> c) { for (E e : c) add(e); return true; }
@Override public boolean containsAll(Collection<?> c) { for (Object o : c) { if (!contains(o)) return false; } return true; }
@Override public boolean removeAll(Collection<?> c) { for (Object o : c) remove(o); return true; }
public ConcurrentHashSet(@NonNull Collection<E> collection) { this(); addAll(collection); }