### Question:
PreferencesProvider { public synchronized void removeAuthenticationFailedFlag() { OPFLog.logMethod(); updateAppVersion(); preferences.remove(KEY_AUTHENTICATION_FAILED_FLAG); } private  PreferencesProvider(@NonNull final Context context); @SuppressWarnings("PMD.NonThreadSafeSingleton") @NonNull static PreferencesProvider getInstance(@NonNull final Context context); @Nullable synchronized String getRegistrationId(); synchronized void saveRegistrationId(@Nullable final String registrationId); synchronized boolean isAuthenticationFailed(); synchronized void saveAuthenticationFailedFlag(); synchronized void removeAuthenticationFailedFlag(); synchronized void reset(); static final int NO_SAVED_APP_VERSION; }### Answer:
@Test public void testRemoveAuthenticationFailedFlag() { preferences.put(KEY_AUTHENTICATION_FAILED_FLAG, true); preferencesProvider.removeAuthenticationFailedFlag(); assertNull(preferences.getBoolean(KEY_AUTHENTICATION_FAILED_FLAG)); preferences.put(KEY_AUTHENTICATION_FAILED_FLAG, false); preferencesProvider.removeAuthenticationFailedFlag(); assertNull(preferences.getBoolean(KEY_AUTHENTICATION_FAILED_FLAG)); }