Change cia-has-selected test (#965)

src/validations/constraints/fedramp-external-constraints.xml

@@ -295,7 +295,7 @@
                 <prop namespace="https://docs.oasis-open.org/sarif/sarif/v2.1.0" name="help-url" value="https://automate.fedramp.gov/documentation/ssp/4-ssp-template-to-oscal-mapping/#system-information-and-information-types"/>
                 <message>When SP 800-60 base and selected impacts levels differ for a given information type, the SSP MUST include a justification for the difference.</message>
             </expect>
-            <expect id="cia-impact-has-selected" target="system-information/information-type/(confidentiality-impact | integrity-impact | availability-impact)" test="selected" level="ERROR">
+            <expect id="cia-impact-has-selected" target="system-information/information-type/(confidentiality-impact | integrity-impact | availability-impact)" test="exists(selected)" level="ERROR">
                 <formal-name>Cia Impact Has Selected</formal-name>
                 <prop namespace="https://docs.oasis-open.org/sarif/sarif/v2.1.0" name="help-url" value="https://automate.fedramp.gov/documentation/ssp/4-ssp-template-to-oscal-mapping/#system-information-and-information-types"/>
                 <message>A FedRAMP SSP information type confidentiality, integrity, or availability impact MUST specify the selected impact.</message>