assertFalse(auth.isClosed());

        // Close the authenticator
        auth.close();

        // Verify it's closed
        assertTrue(auth.isClosed());
        // Cannot check password after closing as it now throws IllegalStateException
        // This is actually good security practice - closed authenticators cannot be accessed

        // Verify multiple closes don't cause issues

import java.nio.charset.Charset;

/**
 * A destination to which bytes can be written, such as a file. Unlike an {@link OutputStream}, a
 * {@code ByteSink} is not an open, stateful stream that can be written to and closed. Instead, it
 * is an immutable <i>supplier</i> of {@code OutputStream} instances.
 *
 * <p>{@code ByteSink} provides two kinds of methods:
 *
 * <ul>

import java.nio.charset.Charset;

/**
 * A destination to which bytes can be written, such as a file. Unlike an {@link OutputStream}, a
 * {@code ByteSink} is not an open, stateful stream that can be written to and closed. Instead, it
 * is an immutable <i>supplier</i> of {@code OutputStream} instances.
 *
 * <p>{@code ByteSink} provides two kinds of methods:
 *
 * <ul>

 *
 *  * **Closing:** one of the peers on the web socket has initiated a graceful shutdown. The web
 *    socket will continue to transmit already-enqueued messages but will refuse to enqueue new
 *    ones.
 *
 *  * **Closed:** the web socket has transmitted all of its messages and has received all messages
 *    from the peer.
 *
 * Web sockets may fail due to HTTP upgrade problems, connectivity problems, or if either peer

      readControlFrame()
    } else {
      readMessageFrame()
    }
  }

  @Throws(IOException::class, ProtocolException::class)
  private fun readHeader() {
    if (closed) throw IOException("closed")

    // Disable the timeout to read the first byte of a new frame.
    val b0: Int
    val timeoutBefore = source.timeout().timeoutNanos()
    source.timeout().clearTimeout()
    try {

     * @throws SmbException if account is locked out
     */
    public boolean checkAttempt(String username, String sourceIp) throws SmbException {
        if (closed.get()) {
            throw new IllegalStateException("Rate limiter is closed");
        }

        // Check global rate limit
        if (!checkGlobalRateLimit()) {
            totalAttemptsBlocked.incrementAndGet();

     */
    @Test
    public void testClose() throws Exception {
        final NotifyOutputStream out = new NotifyOutputStream();
        CloseableUtil.close(out);
        assertThat(out.getNotify(), is("closed"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testCloseNull() throws Exception {
        CloseableUtil.close((OutputStream) null);
    }

    /**

          val source = Buffer().writeUtf8("hello")
          return object : ForwardingSource(source) {
            override fun close() {
              closed = true
              super.close()
            }
          }.buffer()
        }
      }
    body.source().close()
    assertThat(closed).isTrue()
  }

  @Test
  fun throwingUnderlyingSourceClosesQuietly() {
    val body: ResponseBody =
      object : ResponseBody() {

    public boolean close() throws CIFSException {
        if (!this.closed) {
            Runtime.getRuntime().removeShutdownHook(this);
        }
        return false;
    }

    /**
     * {@inheritDoc}
     *
     * @see java.lang.Thread#run()
     */
    @Override
    public void run() {
        try {
            this.closed = true;
            close();
        } catch (final CIFSException e) {

     *
     * @throws CIFSException if an error occurs during closing
     */
    protected synchronized void doClose() throws CIFSException {
        // otherwise already closed
        if (!this.closed) {
            this.closed = true;
            try {
                doCloseInternal();
            } finally {
                this.next = null;
                this.treeHandle.release();
            }