How to define DataSourceField to get ChackBoxItem for Boolean field

[andy.2003]

Hello,

is there a way I can define a field in the datasource, so that the EditorItem is an CheckBoxItem?
If I use

 <field name="foo" type="boolean" />

the field is rendered as BooleanItem, whhich does not allow null values. But the property of the entity field is defined as java.lang.Boolean, which allows null-values.

[andy.2003]

btw. I found out, that java.lang.Boolean fields are only access throught the get<fieldname> Method and not throught the is<fieldname> Method, which would also be Java-Bean confom.