* array with a nullable element type. But probably they usually want an array with a non-nullable
   * type. That said, we could *accept* a `@Nullable T[]` (which, given that we treat arrays as
   * covariant, would still permit a plain `T[]`) and return a plain `T[]`. But of course that would
   * require its own suppression, since it is also unsound. toArray(T[]) is just a mess from a

    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()

    }

    /**
     * Configures this {@code Builder} to order entries by value according to the specified
     * comparator.
     *
     * <p>The sort order is stable, that is, if two entries have values that compare as equivalent,
     * the entry that was inserted first will be first in the built map's iteration order.
     *
     * @throws IllegalStateException if this method was already called
     * @since 19.0
     */

   * <p><b>Warning:</b> For any given key, every {@code loader} used with it should compute the same
   * value. Otherwise, a call that passes one {@code loader} may return the result of another call
   * with a differently behaving {@code loader}. For example, a call that requests a short timeout
   * for an RPC may wait for a similar call that requests a long timeout, or a call by an

   * returns the elements in the order they are returned by the collection's iterator. The returned
   * array is "safe" in that no references to it are maintained by the collection. The caller is
   * thus free to modify the returned array.
   *
   * <p>This method assumes that the collection size doesn't change while the method is running.
   *
   * <p>TODO(kevinb): support concurrently modified collections?
   *

![Events Diagram](../assets/images/******@****.***)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java
class PrintingEventListener extends EventListener {
  private long callStartNanos;

  private void printEvent(String name) {
    long nowNanos = System.nanoTime();

  /**
   * Asks for {@link Object#equals} and {@link Object#hashCode} to be tested. That is, forwarding
   * wrappers of equal instances should be equal.
   */
  @CanIgnoreReturnValue
  public ForwardingWrapperTester includingEquals() {
    this.testsEquals = true;
    return this;
  }

  /**
   * Tests that the forwarding wrapper returned by {@code wrapperFunction} properly forwards method

 * 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

    assertFalse(listener.healthyCalled);
  }

  /**
   * This covers a bug where if a listener was installed that would stop the manager if any service
   * fails and something failed during startup before service.start was called on all the services,
   * then awaitStopped would deadlock due to an IllegalStateException that was thrown when trying to
   * stop the timer(!).
   */

  private String suiteName;
  private @Nullable Runnable setUp;
  private @Nullable Runnable tearDown;

  // public so that it can be referenced in generated GWT tests.
  @Override
  public void setUp() throws Exception {
    if (setUp != null) {
      setUp.run();
    }
  }

  // public so that it can be referenced in generated GWT tests.
  @Override
  public void tearDown() throws Exception {
    if (tearDown != null) {