}

  /** Returns an {@link EndpointPair} representing the endpoints of an undirected edge. */
  public static <N> EndpointPair<N> unordered(N nodeU, N nodeV) {
    // Swap nodes on purpose to prevent callers from relying on the "ordering" of an unordered pair.
    return new Unordered<>(nodeV, nodeU);
  }

  /** Returns an {@link EndpointPair} representing the endpoints of an edge in {@code graph}. */

 *       elements were added (insertion order)
 * </ul>
 *
 * <p>{@code Network}s built by this class also guarantee that each collection-returning accessor
 * returns a <b>(live) unmodifiable view</b>; see <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#accessor-behavior">the external
 * documentation</a> for details.
 *
 * <p>Examples of use:
 *

 *   <li>orders {@link ValueGraph#nodes()} in the order in which the elements were added (insertion
 *       order)
 * </ul>
 *
 * <p>{@code ValueGraph}s built by this class also guarantee that each collection-returning accessor
 * returns a <b>(live) unmodifiable view</b>; see <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#accessor-behavior">the external
 * documentation</a> for details.
 *
 * <p>Examples of use:
 *

 *     [RealConnection.isEligible] for details.
 *
 *  3. Attempt plans from prior connect attempts for this call. These occur as either follow-ups to
 *     failed connect attempts (such as trying the next [ConnectionSpec]), or as attempts that lost
 *     a race in fast follow-up.
 *
 *  4. If there's no existing connection, make a list of routes (which may require blocking DNS

  /**
   * Creates a suite whose map has some elements filtered out of view.
   *
   * <p>Because the map may be ascending or descending, this test must derive the relative order of
   * these extreme values rather than relying on their regular sort ordering.
   */
  final TestSuite createSubmapSuite(
      FeatureSpecificTestSuiteBuilder<
              ?, ? extends OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>>>
          parentBuilder,

   *
   * The returned client installs a default event listener that gathers debug information. This will
   * be logged if the test fails.
   *
   * This client is also configured to be slightly more deterministic, returning a single IP
   * address for all hosts, regardless of the actual number of IP addresses reported by DNS.
   */
  fun newClient(): OkHttpClient {
    var client = testClient
    if (client == null) {
      client =

    ticker.advance(1, MILLISECONDS);
    assertThat(keySet).containsExactly(2, 3, 4, 5, 6, 7, 8, 9, 0);

    // get(K, Callable) doesn't stop 2 from expiring
    Integer unused = cache.get(2, Callables.returning(-2));
    CacheTesting.drainRecencyQueues(cache);
    ticker.advance(1, MILLISECONDS);
    assertThat(keySet).containsExactly(3, 4, 5, 6, 7, 8, 9, 0);

    // asMap.put saves 3
    cache.asMap().put(3, -3);

   */

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_nullCollectionReferenceEmptySubject() {
    try {
      collection.retainAll(null);
      // Returning successfully is not ideal, but tolerated.
    } catch (NullPointerException tolerated) {
    }
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example { #a-dict-from-the-previous-example }

In the previous example, we were returning a `dict` from our dependency ("dependable"):

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

But then we get a `dict` in the parameter `commons` of the *path operation function*.

    }

    /**
     * Retrieves the character mapping file for the specified dictionary ID.
     * <p>
     * This method looks up the dictionary file and ensures it is a character mapping file
     * before returning it wrapped in an OptionalEntity.
     * </p>
     *
     * @param dictId the dictionary ID to retrieve the character mapping file for