/** Constructor for use by subclasses. */
    public Listener() {}

    /**
     * Called when the service initially becomes healthy.
     *
     * <p>This will be called at most once after all the services have entered the {@linkplain
     * State#RUNNING running} state. If any services fail during start up or {@linkplain

   *       <ul>
   *         <li>UNSET, meaning "null pointer"
   *         <li>one plus an index into the keys, values, and entries arrays
   *       </ul>
   *   <li>another java.util.Map delegate implementation. In most modern JDKs, normal java.util hash
   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we

      setException(t);
      return;
    } finally {
      function = null;
    }

    /*
     * If set()/setValue() throws an Error, we let it propagate. Why? The most likely Error is a
     * StackOverflowError (from deep transform(..., directExecutor()) nesting), and calling
     * setException(stackOverflowError) would fail:
     *

 * is {@code addAndGet(K, long)}, which adds a {@code long} to the value currently associated with
 * {@code K}. If a key has not yet been associated with a value, its implicit value is zero.
 *
 * <p>Most methods in this class treat absent values and zero values identically, as individually
 * documented. Exceptions to this are {@link #containsKey}, {@link #size}, {@link #isEmpty}, {@link
 * #asMap}, and {@link #toString}.
 *

      assertThrows(NullPointerException.class, () -> entry.setValue(null));
      checkValidState(cache);
    }
  }

  /* ---------------- Local utilities -------------- */

  /** Most of the tests in this class run against every one of these caches. */
  private Iterable<LoadingCache<Object, Object>> caches() {
    // lots of different ways to configure a LoadingCache

    // If configured, don't follow redirects between SSL and non-SSL.
    val sameScheme = url.scheme == userResponse.request.url.scheme
    if (!sameScheme && !client.followSslRedirects) return null

    // Most redirects don't include a request body.
    val requestBuilder = userResponse.request.newBuilder()
    if (HttpMethod.permitsRequestBody(method)) {
      val responseCode = userResponse.code
      val maintainBody =

   * will be truncated to [byteCount] bytes.
   *
   * It is an error to call this method after the body has been consumed.
   *
   * **Warning:** this method loads the requested bytes into memory. Most applications should set
   * a modest limit on `byteCount`, such as 1 MiB.
   */
  @Throws(IOException::class)
  fun peekBody(byteCount: Long): ResponseBody {
    val peeked = body.source().peek()

    checkArgument(iterator.hasNext(), "Must be at least 1 hash code to combine.");
    int bits = iterator.next().bits();
    byte[] resultBytes = new byte[bits / 8];
    for (HashCode hashCode : hashCodes) {
      byte[] nextBytes = hashCode.asBytes();
      checkArgument(
          nextBytes.length == resultBytes.length, "All hashcodes must have the same bit length.");

   * href="http://en.wikipedia.org/wiki/Memoization">memoization</a>
   *
   * <p>The returned supplier is thread-safe. The delegate's {@code get()} method will be invoked at
   * most once unless the underlying {@code get()} throws an exception. The supplier's serialized
   * form does not contain the cached value, which will be recalculated when {@code get()} is called
   * on the deserialized instance.
   *

  /** Creates a new {@link Closer}. */
  public static Closer create() {
    return new Closer(SUPPRESSING_SUPPRESSOR);
  }

  @VisibleForTesting final Suppressor suppressor;

  // only need space for 2 elements in most cases, so try to use the smallest array possible
  private final Deque<Closeable> stack = new ArrayDeque<>(4);
  private @Nullable Throwable thrown;

  @VisibleForTesting
  Closer(Suppressor suppressor) {