Clarify whether Fedramp SSP mandates all set parameters are explicitly set in SSP (as opposed to by inheritance from the profile).

[butler54]

Issue description / feature objectives

Parameters in OSCAL can be set in multiple locations (implicitily as a default value in the catalog and profile), explicitly in the profile and SSP.

The open question is whether for a FedRAMP SSP the set-parameter value must explicitly be present or can be via inherentence.