keystone/api-ref/source/v3/samples/admin/auth-application-credential-id-request.json

{
    "auth": {
        "identity": {
            "methods": [
                "application_credential"
            ],
            "application_credential": {
                "id": "423f19a4ac1e4f48bbb4180756e6eb6c",
                "secret": "rEaqvJka48mpv"
            }
        }
    }
}