exec.shutdown();
    exec.awaitTermination(100, MILLISECONDS);
  }

  /**
   * Tests that all listeners complete, even if they were added before or after the future was
   * finishing. Also acts as a concurrency test to make sure the locking is done correctly when a
   * future is finishing so that no listeners can be lost.
   */
  public void testAllListenersCompleteSuccessfully()

 *  6. Read from and close that source.
 *
 * Exchanges that do not have a request body may skip creating and closing the request body.
 * Exchanges that do not have a response body can call
 * [newFixedLengthSource(0)][newFixedLengthSource] and may skip reading and closing that source.
 */
class Http1ExchangeCodec(
  /** The client that configures this stream. May be null for HTTPS proxy tunnels. */

        continue;
      }
      assertWithMessage(
              "To help optimizers, any class that inherits a package-private writeReplace() method"
                  + " should override that method.\n"
                  + "(An override that delegates to the supermethod is fine.)\n"
                  + "%s has no such override despite inheriting writeReplace() from %s",

/**
 * A bounded {@linkplain BlockingQueue blocking queue} backed by an array. This queue orders
 * elements FIFO (first-in-first-out). The head of the queue is that element that has been
 * on the queue the longest time. The tail of the queue is that element that has been on
 * the queue the shortest time. New elements are inserted at the tail of the queue, and the queue
 * retrieval operations obtain elements at the head of the queue.
 *

      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.

    }
  }

  /**
   * Verifies that a collection is immutable.
   *
   * <p>A collection is considered immutable if:
   *
   * <ol>
   *   <li>All its mutation methods result in UnsupportedOperationException, and do not change the
   *       underlying contents.
   *   <li>All methods that return objects that can indirectly mutate the collection throw

   * Returns an immutable sorted multiset containing the given elements sorted by their natural
   * ordering. To create a copy of a {@code SortedMultiset} that preserves the comparator, call
   * {@link #copyOfSorted} instead. This method iterates over {@code elements} at most once.
   *
   * <p>Note that if {@code s} is a {@code Multiset<String>}, then {@code
   * ImmutableSortedMultiset.copyOf(s)} returns an {@code ImmutableSortedMultiset<String>}

  /**
   * Shift Out: A control character indicating that the code combinations which follow shall be
   * interpreted as outside of the character set of the standard code table until a Shift In
   * character is reached.
   *
   * @since 8.0
   */
  public static final byte SO = 14;

  /**
   * Shift In: A control character indicating that the code combinations which follow shall be

  abstract Graph<Integer> createGraph();

  /**
   * A proxy method that adds the node {@code n} to the graph being tested. In case of Immutable
   * graph implementations, this method should replace {@link #graph} with a new graph that includes
   * this node.
   */
  abstract void addNode(Integer n);

  /**
   * A proxy method that adds the edge {@code e} to the graph being tested. In case of Immutable

 * which has a method {@code getParents()} that retrieves its predecessors in a graph:
 *
 * {@snippet :
 * someGraphAlgorithm(startNode, MyNode::getParents);
 * }
 *
 * <p>If you have some other mechanism for returning the predecessors of a node, or one that doesn't
 * return a {@code Iterable<? extends N>}, then you can use a lambda to perform a more general