mock-redfish-server/mockup/redfish/v1/Registries/index.json

{
    "@odata.type": "#MessageRegistryFileCollection.MessageRegistryFileCollection",
    "Name": "MessageRegistryFile collection",
    "@odata.context": "/redfish/v1/$metadata#MessageRegistryFileCollection.MessageRegistryFileCollection",
    "Members": [
        {
            "@odata.id": "/redfish/v1/Registries/1"
        }
    ],
    "Description": "Collection of Message Registry Files",
    "@odata.id": "/redfish/v1/Registries",
    "Members@odata.count": 1
}