This is inconsisted with the text on using https in the introduction. Why is it optional here and mandatory elsewhere?

Existing Wording:

Two optional methods are provided. First, FHIR resources MAY be obtained by passing "prefetched" data from the CDS Client to the CDS Service in the service call. FHIR resources requested in the CDS Service description are passed as key-value pairs, with each key matching a key described in the CDS Service description, and each value being a FHIR resource. Note that in the case of searches, this resource may be a searchset Bundle. If data are to be prefetched, the CDS Service registers a set of "prefetch templates" with the CDS Client, as described in the Prefetch Template section below.

Proposed Wording:

The base URL of the CDS Client's FHIR server.