Wrong deserialization of SelectChoice.value

[ggalmazor]

Problem description

According to the normal constructors of SelectChoice, its value member should never be null. Nevertheless, value could have a null value after deserialization if it was holding an empty string before.

Steps to reproduce the problem

The following test proves this:

@Test
public void value_should_continue_being_an_empty_string_after_deserialization() throws IOException, DeserializationException {
    Scenario scenario = Scenario.init("SelectChoice.getValue() regression test form", html(
        head(
            title("SelectChoice.getValue() regression test form"),
            model(
                mainInstance(t("data id=\"some-form\"",
                    t("the-choice")
                )),
                bind("/data/the-choice").type("string").required()
            )
        ),
        body(select1("/data/the-choice",
            label("Select one choice"),
            item("", "Empty value")
        ))
    ));

    scenario.next();
    assertThat(scenario.getQuestionAtIndex().getChoice(0).getValue(), is(""));

    Scenario deserializedScenario = scenario.serializeAndDeserializeForm();
    deserializedScenario.newInstance();
    deserializedScenario.next();
    assertThat(deserializedScenario.getQuestionAtIndex().getChoice(0).getValue(), is(""));
}

Expected behavior

The value member should not change its value after deserialization.