SingleSelect ListField

The merge caused:

because I moved some methods to the superclass, but when instantiating via reflection it still expects it in the subclass if the dependency is not updated in all projects. solution:
https://github.com/celements/celements-xwiki/pull/11

had the same issue in

Additionally, I added a SingleListField, which is basically the same as a ListField with multiselect(false) but with easier to use generics:

class SingleListField<T> implements ClassField<T>
instead of
class ListField<T> implements ClassField<List<T>>

Type Hierarchy:

• AbstractListField<T, E> implements CustomClassField<T>

  • ListField<T> extends AbstractListField<List<T>, T>

    • DBListField extends ListField<String>

    • CustomListField<T> extends ListField<T>

      • StringListField extends CustomListField<String> (aka StaticListField)

  • SingleListField<T> extends AbstractListField<T, T>

    • CustomSingleListField<T> extends SingleListField<T>

      • StringSingleListField extends CustomSingleListField<String> (aka StaticSingleListField)

This is a problem for singleSelect ListField<T> extends ClassField<List<T>> . when calling
filter(listField, Arrays.asList(val1, val2))
it does not in fact call the filter with an OR-List, but merely the key/value filter (since value is expected to be of type List). the right call would be with a List<List<T>>:
filter(listField, Arrays.asList(Arrays.asList(val1), Arrays.asList(val2)))

This behaviour isn't intuitive for singleSelect ListFields since one expects only one value by default, therefore I propose explicit handlig for these kind of ClassFields