public static Gson instance() {
        return SingletonHolder.INSTANCE;
    }
@Test
    void rejectsSerializationOfDESEncrypter() {
        final IllegalArgumentException e = assertThrows(IllegalArgumentException.class, () ->
                Serialization.instance().toJson(new DESEncrypter(mock(DESCipherProvider.class))));
        assertEquals(format("Refusing to serialize a %s instance and leak security details!", DESEncrypter.class.getName()), e.getMessage());
    }