request.header("If-Modified-Since") != null || request.header("If-None-Match") != null
  }

  companion object {
    /** Returns true if [response] can be stored to later serve another request. */
    fun isCacheable(
      response: Response,
      request: Request,
    ): Boolean {
      // Always go to network for uncacheable response codes (RFC 7231 section 6.1), This

  - [Changelog since v1.13.11](#changelog-since-v11311)
    - [Other notable changes](#other-notable-changes)
- [v1.13.11](#v11311)
  - [Downloads for v1.13.11](#downloads-for-v11311)
    - [Client Binaries](#client-binaries-1)
    - [Server Binaries](#server-binaries-1)
    - [Node Binaries](#node-binaries-1)
  - [Changelog since v1.13.10](#changelog-since-v11310)
    - [Other notable changes](#other-notable-changes-1)
- [v1.13.10](#v11310)

    - [Action Required](#action-required)
    - [Other notable changes](#other-notable-changes)
- [v1.9.10](#v1910)
  - [Downloads for v1.9.10](#downloads-for-v1910)
    - [Client Binaries](#client-binaries-1)
    - [Server Binaries](#server-binaries-1)
    - [Node Binaries](#node-binaries-1)
  - [Changelog since v1.9.9](#changelog-since-v199)
    - [Other notable changes](#other-notable-changes-1)
- [v1.9.9](#v199)

   *
   * @throws IOException if an I/O error occurs while reading from this source or {@code other}
   */
  public boolean contentEquals(ByteSource other) throws IOException {
    checkNotNull(other);

    Closer closer = Closer.create();
    try {
      return ByteStreams.contentsEqual(
          closer.register(openStream()), closer.register(other.openStream()));
    } catch (Throwable e) {
      throw closer.rethrow(e);

  - [Changelog since v1.11.9](#changelog-since-v1119)
    - [Other notable changes](#other-notable-changes)
- [v1.11.9](#v1119)
  - [Downloads for v1.11.9](#downloads-for-v1119)
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    - [Server Binaries](#server-binaries-1)
    - [Node Binaries](#node-binaries-1)
  - [Changelog since v1.11.8](#changelog-since-v1118)
    - [Other notable changes](#other-notable-changes-1)
- [v1.11.8](#v1118)

 *
 *  * Application Layer Protocol Negotiation (ALPN) enables the HTTPS port (443) to be used to
 *    negotiate HTTP/2.
 *
 * Unfortunately, older HTTPS servers refuse to connect when such options are presented. Rather than
 * avoiding these options entirely, this class allows a connection to be attempted with modern
 * options and then retried without them should the attempt fail.
 *
 * ## Connection Reuse
 *

   * undocumented and subject to change.
   *
   * <p>This method is safe to use even when {@code sortedMultiset} is a synchronized or concurrent
   * collection that is currently being modified by another thread.
   *
   * @throws NullPointerException if {@code sortedMultiset} or any of its elements is null
   */
  public static <E> ImmutableSortedMultiset<E> copyOfSorted(SortedMultiset<E> sortedMultiset) {

    checkNotNull(runnable, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");

    // Lock while we check state. We must maintain the lock while adding the new pair so that
    // another thread can't run the list out from under us. We only add to the list if we have not
    // yet started execution.
    synchronized (this) {
      if (!executed) {

  // 0x89abcd80. To this is added (or'd) the `next` value, which is an index within `entries`
  // (and therefore within `keys` and `values`) of another entry that has the same short hash
  // value. In our example, it would be another entry for a key whose short hash is also 0x6f.
  //
  // Essentially, then, `table[h]` gives us the start of a linked list in `entries`, where every

 * guarantee that the new value will be fully visible to the other threads. To guarantee that
 * modifications are visible, synchronize access to the table. Unlike other {@code Table}
 * implementations, synchronization is unnecessary between a thread that writes to one cell and a
 * thread that reads from another.
 *
 * <p>See the Guava User Guide article on <a href=