@Override
  protected boolean isValidFragment(String fragmentName) {
    // PreferenceActivity is vulnerable to Fragment Injection prior to KitKat
    // (http://goo.gl/jz36Ip)
    // Override this to always return false as we do not use Fragment for Preference.
    return false;
  }
Base class for {@link AppCompatPreferenceActivity} instances to make them more testable.
java/com/google/android/apps/authenticator/testability/TestablePreferenceActivity.java