@Override
    public void setSession(MavenSession session) {
        AtomicReference<MavenSession> reference = DefaultLegacySupport.SESSION.get();
        if (reference != null) {
            reference.set(null);
        }

        if (session == null && reference != null) {
            DefaultLegacySupport.SESSION.remove();
        } else {
            DefaultLegacySupport.SESSION.set(new AtomicReference<>(session));
        }
    }

    // Populate the results list with null initially.
    for (int i = 0; i < futures.size(); ++i) {
      values.add(null);
    }

    this.values = values;
  }

  @Override
  final void collectOneValue(int index, @ParametricNullness V returnValue) {
    @RetainedLocalRef List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      localValues.set(index, new Present<>(returnValue));

        }
    }

    @Test
    void handlesAbsentTransferSource() throws InterruptedException, TransferCancelledException {
        TransferResource resource = new TransferResource(null, null, "http://maven.org/test/test-resource", null, null);

        RepositorySystemSession session = Mockito.mock(RepositorySystemSession.class);
        TransferListener delegate = Mockito.mock(TransferListener.class);

     * has a current project, its plugin repositories will be used as well.
     *
     * @param plugin The plugin for which to resolve a version, must not be {@code null}.
     * @param session The Maven session to use, must not be {@code null}.
     */
    public DefaultPluginVersionRequest(Plugin plugin, MavenSession session) {
        setGroupId(plugin.getGroupId());
        setArtifactId(plugin.getArtifactId());

    assertEquals("correct", f.apply(new Object()));
    assertEquals("correct", f.apply(null));

    Function<@Nullable Object, @Nullable String> g = Functions.constant(null);
    assertEquals(null, g.apply(2));
    assertEquals(null, g.apply(null));

    new EqualsTester()
        .addEqualityGroup(f, Functions.constant("correct"))

 * <pre>{@code
 * // Find child element
 * Element child = parent.child("version").orElse(null);
 *
 * // Check if child exists
 * boolean hasVersion = parent.child("version").isPresent();
 *
 * // Get child text content
 * String version = parent.child("version")
 *     .map(Element::textContent)
 *     .orElse(null);
 *
 * // Get trimmed text content
 * String trimmedVersion = parent.child("version")

   *
   * @param escaper the non-null escaper to test
   */
  public static void assertBasic(Escaper escaper) throws IOException {
    // Escapers operate on characters: no characters, no escaping.
    Assert.assertEquals("", escaper.escape(""));
    // Assert that escapers throw null pointer exceptions.
    try {
      escaper.escape((String) null);

interface ModelCacheTag<T> {

    /**
     * Gets the name of the tag.
     *
     * @return The name of the tag, must not be {@code null}.
     */
    String getName();

    /**
     * Gets the type of data associated with this tag.
     *
     * @return The type of data, must not be {@code null}.
     */
    Class<T> getType();

    /**

   *
   * @param escaper the non-null escaper to test
   */
  public static void assertBasic(Escaper escaper) throws IOException {
    // Escapers operate on characters: no characters, no escaping.
    Assert.assertEquals("", escaper.escape(""));
    // Assert that escapers throw null pointer exceptions.
    try {
      escaper.escape((String) null);

  public void testPutIfAbsent_nullKeyUnsupported() {
    assertThrows(NullPointerException.class, () -> getMap().putIfAbsent(null, v3()));
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported putIfAbsent(null, value)");
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUES)