If there was always only one top-level field and everything else was inside that, it could be externally tagged, but it’s definitely just untagged here, because

If there was always only one top-level field and everything else was inside that, it could be externally tagged, but it’s definitely just untagged here, because #/components/examples/errorInvalidJson/value (line 4397) shows an error body with multiple top-level fields: {"error":"Invalid JSON.","detail":"…","location":{"offset":0,"line":1,"column":0}}. Externally tagged would be {"error":{"message":"Invalid JSON.","detail":"…","location":{…}}}.