Many of the CPG profiles constrain relatedArtifact.url to be 1..1 (required). In many cases, however, it may be better to refer to the related artifact using resource or document instead of url. This is a problem, however, because the FHIR spec for RelatedArtifact.url states:

If a document or resource element is present, this element SHALL NOT be provided (use the url or reference in the Attachment or resource reference).

Therefore, by requiring relatedArtifact.url you are prohibiting relatedArtifact.resource and relatedArtifact.document. I've noticed that many of the examples in the IG actually do not have relatedArtifact.url, but use relatedArtifact.resource instead.  I think the examples are right, so the profiles need to be modified to remove the 1..1 constraint on relatedArtifact.url.

Also, given that relatedArtifact.resource is, in fact, often the right choice, it should be considered for a MustSupport flag (since relatedArtifact.url is already marked MustSupport.