Discrepancy between Measure.type and Group.extension['cqfm-type']

Measure.type cardinality is 0..*. However, the extension for 'cqfm-type' is 0..1. If it is reasonable to assume that a measure may have more than one type, can it not also be assumed that a group would have more than one type? If so, then cardinality for group extension for 'cqfm-type' needs to be updated.