@Test
public void invokeNull2ParamsMethod() {

    FunctionTestUtil.assertResultError(substringFunction.invoke((String) null, null), InvalidParametersEvent.class);
    FunctionTestUtil.assertResultError(substringFunction.invoke("test", null), InvalidParametersEvent.class);
    FunctionTestUtil.assertResultError(substringFunction.invoke(null, 0), InvalidParametersEvent.class);
}