3.8.1.1 getObjectRelationships inputs needs clarification

includeSubRealtionshipTypes is a required parameter, yet it influences the behavior of typeId, an optional parameter. This seems to make typeId also required, or else includeSubRelationshipTypes should be optional (and have a default of TRUE so that it behaves rationally when typeId is unset, and the service is required to return relationships of all sub-types of cmis:relationship.