public <T> void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(TypeToken.class);
    new NullPointerTester()
        .setDefault(TypeParameter.class, new TypeParameter<T>() {})
        .testAllPublicInstanceMethods(TypeToken.of(String.class));
  }

  private static class Assignability<From, To> {

    boolean isAssignable() {