final Type t3 = m3.getGenericReturnType();
        assertThat(GenericsUtil.isTypeOf(t3, Map.class), is(true));
        assertThat(WildcardType.class.isInstance(GenericsUtil.getKeyTypeOfMap(t3)), is(true));
        assertThat(WildcardType.class.isInstance(GenericsUtil.getValueTypeOfMap(t3)), is(true));
    }

    /**
     * @throws Exception
     */
    public void testGetTypeVariableMap() throws Exception {

   *
   * <p><b>Discouraged:</b> Prefer using {@code clazz::isInstance} or {@code x -> x instanceof
   * Clazz}, but note that lambdas do not have human-readable {@link #toString()} representations
   * and are not serializable.
   */
  @GwtIncompatible // Class.isInstance
  public static <T extends @Nullable Object> Predicate<T> instanceOf(Class<?> clazz) {

   * This does perform a little more work than necessary, so another option is to insert an
   * unchecked cast at some later point:
   *
   * {@snippet :
   * @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =
   *     (ImmutableList) stream.filter(NewType.class::isInstance).collect(toImmutableList());
   * }
   */

   * This does perform a little more work than necessary, so another option is to insert an
   * unchecked cast at some later point:
   *
   * {@snippet :
   * @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =
   *     (ImmutableList) stream.filter(NewType.class::isInstance).collect(toImmutableList());
   * }
   */

   */
  @GwtIncompatible // Class.cast, Class.isInstance
  public static <X extends Throwable> void throwIfInstanceOf(
      Throwable throwable, Class<X> declaredType) throws X {
    checkNotNull(throwable);
    if (declaredType.isInstance(throwable)) {
      throw declaredType.cast(throwable);
    }
  }

  /**
   * Propagates {@code throwable} exactly as-is, if and only if it is an instance of {@code
   * declaredType}. Example usage:

        // Act & Assert
        // unwrap to interface itself should return same instance
        CredentialsInternal unwrapped = creds.unwrap(CredentialsInternal.class);
        assertNotNull(unwrapped, "unwrap to CredentialsInternal returns instance");
        assertSame(creds, unwrapped, "unwrap returns the same object instance");

        // unwrap to unrelated type should return null (use another Credentials implementation)

   * This does perform a little more work than necessary, so another option is to insert an
   * unchecked cast at some later point:
   *
   * {@snippet :
   * @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =
   *     (ImmutableList) stream.filter(NewType.class::isInstance).collect(toImmutableList());
   * }
   */

internal fun <T> readFieldOrNull(
  instance: Any,
  fieldType: Class<T>,
  fieldName: String,
): T? {
  var c: Class<*> = instance.javaClass
  while (c != Any::class.java) {
    try {
      val field = c.getDeclaredField(fieldName)
      field.isAccessible = true
      val value = field.get(instance)
      return if (!fieldType.isInstance(value)) null else fieldType.cast(value)

   * This does perform a little more work than necessary, so another option is to insert an
   * unchecked cast at some later point:
   *
   * {@snippet :
   * @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =
   *     (ImmutableList) stream.filter(NewType.class::isInstance).collect(toImmutableList());
   * }
   */

      }
    } catch (Throwable t) {
      // ensure we really catch *everything*
    }

    return JavaLittleEndianBytes.INSTANCE;
  }

  // Compare AbstractFuture.VarHandleAtomicHelperMaker.
  private enum VarHandleLittleEndianBytesMaker {
    INSTANCE {
      /**
       * Implementation used by non-J2ObjC environments (aside, of course, from those that have