* is transmitted. If you cannot ensure that your client and server both support HTTP/2, do not
   * use this feature.
   *
   * ### Duplex APIs
   *
   * With regular request bodies it is not legal to write bytes to the sink passed to
   * [RequestBody.writeTo] after that method returns. For duplex requests bodies that condition is

 * {@link #runOneIteration} that will be executed periodically as specified by its {@link
 * Scheduler}. When this service is asked to stop via {@link #stopAsync} it will cancel the periodic
 * task (but not interrupt it) and wait for it to stop before running the {@link #shutDown} method.
 *
 * <p>Subclasses are guaranteed that the life cycle methods ({@link #runOneIteration}, {@link

  <exclude name="**/testing/**"/>
</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see

   *
   * <p>The returned iterable's iterator supports {@code remove()} if the iterator of the underlying
   * iterable supports it. Note that it is <i>not</i> possible to delete the last skipped element by
   * immediately calling {@code remove()} on that iterator, as the {@code Iterator} contract states

    // Run a task on the composed Executor that interrupts its thread (i.e. this thread).
    fakePool.execute(
        new Runnable() {
          @Override
          public void run() {
            Thread.currentThread().interrupt();
          }
        });
    // Run a task that expects that it is not interrupted while it is running.
    e.execute(
        new Runnable() {

/**
 * A collection that supports order-independent equality, like {@link Set}, but may have duplicate
 * elements. A multiset is also sometimes called a <i>bag</i>.
 *
 * <p>Elements of a multiset that are equal to one another are referred to as <i>occurrences</i> of
 * the same single element. The total number of occurrences of an element in a multiset is called

      throw e.getCause();
    }
  }

  /**
   * Verify that the listener completes in a reasonable amount of time, and Asserts that the future
   * throws an {@code ExecutableException} and that the cause of the {@code ExecutableException} is
   * {@code expectedCause}.
   */
  public void assertException(Throwable expectedCause) throws Exception {
    // Verify that the listener executed in a reasonable amount of time.

   * https://github.com/jspecify/jspecify-reference-checker/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
   * and https://github.com/jspecify/jspecify/issues/490.
   *
   * (Perhaps it should also have required that its cause was a RuntimeException. However, that

 *
 * Implementations authenticate by returning a follow-up request that includes an authorization
 * header, or they may decline the challenge by returning null. In this case the unauthenticated
 * response will be returned to the caller that triggered it.
 *
 * Implementations should check if the initial request already included an attempt to
 * authenticate. If so it is likely that further attempts will not be useful and the authenticator

    }

    /**
     * Returns a filter for directories that may contain paths accepted by the given matcher.
     * The given path matcher should be an instance created by this service.
     * The path matcher returned by this method expects directory paths.
     * If that matcher returns {@code false}, then the directory will definitively not contain