f:ValueSet/f:compose/f:include extension with URL = 'http://hl7.at/fhir/HL7ATCoreProfiles/5.0.0/StructureDefinition/at-core-ext-valueset-systemoid': maximum cardinality of 'extension' is 1 f:ValueSet/f:expansion/f:contains extension with URL = 'http://hl7.at/fhir/HL7ATCoreProfiles/5.0.0/StructureDefinition/at-core-ext-valueset-systemoid': maximum cardinality of 'extension' is 1