_repropagationCondition() {
    return false;
  }
Usually, we don't use composition in regular LionFields (non choice-groups). Here we use a LionSelect(Rich) inside.
We don't want to repropagate any children, since an Application Developer is not concerned with these internals (see repropate logic in FormControlMixin)
Also, we don't want to give (wrong) info to InteractionStateMixin, that will set the wrong interaction states based on child info.
TODO: Make "this._repropagationRole !== 'child'" the default for FormControlMixin
(so that FormControls used within are never repropagated for LionFields)
@protected
@configure FormControlMixin: don't repropagate any children