*
   * <p>Under j2objc, the necessary APIs exist, but some (perhaps all) return stub values, like
   * empty arrays. Presumably {@link NullPointerTester} could likewise misbehave under j2objc, but I
   * don't know that anyone uses it there, anyway.
   */
  private enum NullnessAnnotationReader {
    FROM_DECLARATION_AND_TYPE_USE_ANNOTATIONS {
      @Override
      boolean isNullable(Invokable<?, ?> invokable) {

 * fallout from trying to switch. I would be shocked if the switch would offer benefits to anywhere
 * near enough users to justify the costs.
 *
 * Fortunately, if anyone does want to use a Converter as a `Function<@Nullable A, @Nullable B>`,
 * it's easy to get one: `converter::convert`.
 *
 * [*] In annotating this class, we're ignoring LegacyConverter.
 */