public boolean retainAll(Collection<?> elementsToRetain) {
    throw up();
  }

  @Override
  public void clear() {
    throw up();
  }

  private static UnsupportedOperationException up() {
    throw new UnsupportedOperationException();
  }

    private boolean throwOnShutDown = false;

    @Override
    protected void run() {
      throw new UnsupportedOperationException("kaboom!");
    }

    @Override
    protected void shutDown() {
      shutDownCalled = true;
      if (throwOnShutDown) {
        throw new UnsupportedOperationException("double kaboom!");
      }
    }

    @Override
    protected Executor executor() {

                    handlerStack.addFirst(handler);
                    tagStack.addFirst(name);
                    return;
                }
            }
            throw new UnsupportedOperationException();
        }

        @Override
        void onEndHtmlElement(String name) {
            if (!tagStack.isEmpty() && tagStack.getFirst().equals(name)) {
                tagStack.removeFirst();

    }

    @Override
    public void addHandlers(Map<String, ArtifactHandler> handlers) {
        throw new UnsupportedOperationException("Adding handlers programmatically is not supported anymore");
    }

    @Deprecated
    public Set<String> getHandlerTypes() {
        throw new UnsupportedOperationException("Querying handlers programmatically is not supported anymore");
    }

  }

  public void test_useForNull_skipNulls() {
    Joiner j = Joiner.on("x").useForNull("y");
    assertThrows(UnsupportedOperationException.class, j::skipNulls);
  }

  public void test_skipNulls_useForNull() {
    Joiner j = Joiner.on("x").skipNulls();
    assertThrows(UnsupportedOperationException.class, () -> j.useForNull("y"));
  }

  public void test_useForNull_twice() {

  public final boolean addAll(int index, Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final E set(int index, E element) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final void add(int index, E element) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final E remove(int index) {

    /**
     *
     */
    private void doClose() {
        this.treeHandle.release();
        this.next = null;
    }

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

      Runnable command, long initialDelay, long period, TimeUnit unit) {
    throw new UnsupportedOperationException("scheduleAtFixedRate is not supported.");
  }

  @Override
  public ListenableScheduledFuture<?> scheduleWithFixedDelay(
      Runnable command, long initialDelay, long delay, TimeUnit unit) {
    throw new UnsupportedOperationException("scheduleWithFixedDelay is not supported.");
  }

    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemoveUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> getMultiset().remove(e0(), 2));
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveZeroNoOp() {
    int originalCount = getMultiset().count(e0());

      Runnable command, long initialDelay, long period, TimeUnit unit) {
    throw new UnsupportedOperationException("scheduleAtFixedRate is not supported.");
  }

  @Override
  public ListenableScheduledFuture<?> scheduleWithFixedDelay(
      Runnable command, long initialDelay, long delay, TimeUnit unit) {
    throw new UnsupportedOperationException("scheduleWithFixedDelay is not supported.");
  }