61     Empty(EmptyConstraint),  enumerator
82         Self::Empty(EmptyConstraint {})  in default()
219             Self::Empty(_) => true,  in is_empty()
244             Self::Empty(constraint) => ResolvedMediaTrackConstraint::Empty(constraint),  in into_resolved()
279     Empty(EmptyConstraint),  enumerator
294         Self::Empty(EmptyConstraint {})  in default()
301             Self::Empty(_constraint) => "<empty>".fmt(f),  in fmt()
369             Self::Empty(_constraint) => false,  in is_required()
381             Self::Empty(_constraint) => true,  in is_empty()
399             Self::Empty(constraint) => Self::Empty(constraint),  in into_required_only()
584         let empty_subject = Subject::Empty(EmptyConstraint {});  in is_empty()
605                 Subject::Empty(EmptyConstraint {}),  in to_resolved()
606                 ResolvedMediaTrackConstraint::Empty(EmptyConstraint {}),  in to_resolved()
653                 (Subject::Empty(EmptyConstraint {}), "<empty>"),  in to_string()
698         let subject = Subject::Empty(EmptyConstraint {});  in empty()