http://hl7.org/fhir/StructureDefinition/operationoutcome-file|5.2.0

Identifies the source file where the issue is found (when there are multiple source files).
typedestination
baseDefinitionhttp://hl7.org/fhir/StructureDefinition/Extension
typehttp://hl7.org/fhir/StructureDefinition/Extension
Extension.value[x].typehttp://hl7.org/fhir/StructureDefinition/string