public void testPrivateClass() {
    NullPointerTester tester = new NullPointerTester();
    for (Constructor<?> constructor :
        PrivateClassWithPrivateConstructor.class.getDeclaredConstructors()) {
      tester.testConstructor(constructor);
    }
  }

  private interface Foo<T> {
    void doSomething(T bar, Integer baz);
  }

  private static class StringFoo implements Foo<String> {

    @Override