* Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 * <i>missing</i> information and the other is not. The {@link #convert} method handles this null
 * behavior for all converters; implementations of {@link #doForward} and {@link #doBackward} are
 * guaranteed to never be passed {@code null}, and must never return {@code null}.
 *
 * <h3>Common ways to use</h3>
 *
 * <p>Getting a converter:
 *
 * <ul>
 *   <li>Use a provided converter implementation, such as {@link Enums#stringConverter}, {@link

        for (test in testInstances) {
          assertThat(test.dispatcherA.closed).isTrue()
          assertThat(test.dispatcherB.closed).isTrue()
          assertThat(test.dispatcherC.closed).isFalse() // Never started.
        }
        testInstances.clear()

        // No assertion that serverC and serverD are closed, because the MockWebServerExtension
        // runs after this callback.
        if (false) {

     * cache is populated but the state of the cache must not change so we need to make a copy.
     *
     * @param data The data to store in the cache, must not be {@code null}.
     * @return The data being stored in the cache, never {@code null}.
     */
    T intoCache(T data);

    /**
     * Creates a copy of the data suitable for retrieval from the cache. The retrieved data can be mutated after the

     * The id uniquely identifies this <i>dependency type</i>.
     *
     * @return the id of this type, never {@code null}.
     */
    @Nonnull
    @Override
    String id();

    /**
     * Returns the dependency type language.
     *
     * @return the language of this type, never {@code null}.
     */
    @Nonnull
    Language getLanguage();

    /**

     *            null}.
     * @param session The repository session to use for resolving the plugin's main artifact, must not be {@code null}.
     * @return The resolved plugin artifact, never {@code null}.
     * @throws PluginResolutionException If the plugin artifact could not be resolved.
     */
    Artifact resolve(Plugin plugin, List<RemoteRepository> repositories, RepositorySystemSession session)

     *            be {@code null}.
     * @param request The project building request holding further settings like repository settings, must not be
     *            {@code null}.
     * @return The effective artifact repositories, never {@code null}.
     * @throws InvalidRepositoryException
     */
    List<ArtifactRepository> createArtifactRepositories(
            List<Repository> pomRepositories,
            List<ArtifactRepository> externalRepositories,

     *            null}.
     * @param session The repository session to use for resolving the plugin's main artifact, must not be {@code null}.
     * @return The plugin descriptor, never {@code null}.
     */
    PluginDescriptor getPluginDescriptor(
            Plugin plugin, List<RemoteRepository> repositories, RepositorySystemSession session)

   * value for which {@link Comparable#compareTo(Object)} never returns a positive value for any
   * input of type {@code C}.
   *
   * <p>The default implementation throws {@code NoSuchElementException}.
   *
   * @return the minimum value of type {@code C}; never null
   * @throws NoSuchElementException if the type has no (practical) minimum value; for example,