buf.append("},");
        final Threads threads = jvmStats.getThreads();
        buf.append("\"threads\":{");
        append(buf, "count", () -> threads.getCount()).append(',');
        append(buf, "peak", () -> threads.getPeakCount());
        buf.append("},");
        final Classes classes = jvmStats.getClasses();
        buf.append("\"classes\":{");

            }
          }
        };

    assertEquals(0, (int) iter.peek());
    assertEquals(0, (int) iter.peek());
    assertTrue(iter.hasNext());
    assertEquals(0, (int) iter.peek());
    assertEquals(0, (int) iter.next());

    assertEquals(1, (int) iter.peek());
    assertEquals(1, (int) iter.next());

    /*
     * We test peek() after various calls to make sure that one bad call doesn't interfere with its

    assertEquals(
        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(

  @CollectionSize.Require(ZERO)
  public void testPeek_empty() {
    assertNull("emptyQueue.peek() should return null", getQueue().peek());
    expectUnchanged();
  }

  @CollectionSize.Require(ONE)
  public void testPeek_size1() {
    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)

   *
   * <p>Calls to {@code peek()} should not change the state of the iteration, except that it
   * <i>may</i> prevent removal of the most recent element via {@link #remove()}.
   *
   * @throws NoSuchElementException if the iteration has no more elements according to {@link
   *     #hasNext()}
   */
  @ParametricNullness
  E peek();

  /**
   * {@inheritDoc}
   *

@Throws(EOFException::class)
private fun Buffer.readChallengeHeader(result: MutableList<Challenge>) {
  var peek: String? = null

  while (true) {
    // Read a scheme name for this challenge if we don't have one already.
    if (peek == null) {
      skipCommasAndWhitespace()
      peek = readToken()
      if (peek == null) return
    }

    val schemeName = peek

    // Read a token68, a sequence of parameters, or nothing.

  @CollectionSize.Require(ZERO)
  public void testPeek_empty() {
    assertNull("emptyQueue.peek() should return null", getQueue().peek());
    expectUnchanged();
  }

  @CollectionSize.Require(ONE)
  public void testPeek_size1() {
    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)

    // other threads waiting on take() will also return.
    if (result == DEAD_LETTER) responseQueue.add(DEAD_LETTER)

    return result
  }

  public override fun peek(): MockResponse = responseQueue.peek() ?: failFastResponse ?: super.peek()

  public open fun enqueue(response: MockResponse) {
    responseQueue.add(response)
  }

  public open fun clear() {
    responseQueue.clear()
  }

 * an HTTP call to a remote server.
 */
interface TrailersSource {
  @Throws(IOException::class)
  fun peek(): Headers? = null

  @Throws(IOException::class)
  fun get(): Headers

  companion object {
    @JvmField
    val EMPTY: TrailersSource =
      object : TrailersSource {
        override fun peek() = Headers.EMPTY

        override fun get() = Headers.EMPTY
      }
  }

    public boolean remove(Object object) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove(object);
    }

    @Override
    public @Nullable E peek() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.peek();
    }

    @Override
    public E element() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.element();
    }

    @Override