@Test(expected = NullPointerException.class)
public void tryToInvokeIsMarkedWithOnlyNullMarker() {

    final JavaValueFieldDefinition<Integer> underTest =
            JavaValueFieldDefinition.newInstance(KNOWN_JSON_POINTER, int.class, JsonValue::isNumber,
                    JsonValue::asInt, knownFieldMarkers);
    underTest.isMarkedAs(null);
}