assertEquals(
        "getOrDefault(present, def) should return the associated value",
        v0(),
        getMap().getOrDefault(k0(), v3()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testGetOrDefault_presentNullDefault() {
    assertEquals(
        "getOrDefault(present, null) should return the associated value",
        v0(),
        getMap().getOrDefault(k0(), null));
  }

     *
     * - a `getFooOrDefault(@CheckForNull Foo defaultValue)` method that returns
     *   `map.getOrDefault(FOO_KEY, defaultValue)`
     *
     * - a call that consults a chain of maps, as in `mapA.getOrDefault(key, mapB.getOrDefault(key,
     *   ...))`
     *
     * So it makes sense for the parameter (and thus the return type) to be @CheckForNull.
     *
     * Two other points:
     *

     *
     * - a `getFooOrDefault(@CheckForNull Foo defaultValue)` method that returns
     *   `map.getOrDefault(FOO_KEY, defaultValue)`
     *
     * - a call that consults a chain of maps, as in `mapA.getOrDefault(key, mapB.getOrDefault(key,
     *   ...))`
     *
     * So it makes sense for the parameter (and thus the return type) to be @CheckForNull.
     *

  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNullPointerExceptions() {
    new NullPointerTester()
        .setDefault(Enum.class, SomeEnum.A)
        .setDefault(Class.class, SomeEnum.class) // for newEnumSet
        .testAllPublicStaticMethods(Sets.class);
  }

  public void testNewSetFromMap() {

   * runner would run it even if we did, but part of the problem is b/230620681.
   */

  private static final FileSystem FS = FileSystems.getDefault();

  private static Path root() {
    return FS.getRootDirectories().iterator().next();
  }

  private Path tempDir;

  @Override
  protected void setUp() throws Exception {

      synchronized (mutex) {
        return delegate().get(key);
      }
    }

    @Override
    @CheckForNull
    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
      synchronized (mutex) {
        return delegate().getOrDefault(key, defaultValue);
      }
    }

    @Override
    public boolean isEmpty() {
      synchronized (mutex) {