// +optional
  optional UserSubject user = 2;

  // `group` matches based on user group name.
  // +optional
  optional GroupSubject group = 3;

  // `serviceAccount` matches ServiceAccounts.
  // +optional
  optional ServiceAccountSubject serviceAccount = 4;
}

// UserSubject holds detailed information for user-kind subject.
message UserSubject {

  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;

  // provisioner indicates the type of the provisioner.
  optional string provisioner = 2;

  // parameters holds the parameters for the provisioner that should
  // create volumes of this storage class.
  // +optional
  map<string, string> parameters = 3;

  // APIGroups, APIVersions, Resources, etc.
  optional Rule rule = 2;
}

// ServiceReference holds a reference to Service.legacy.k8s.io
message ServiceReference {
  // `namespace` is the namespace of the service.
  // Required
  optional string namespace = 1;

  // `name` is the name of the service.
  // Required
  optional string name = 2;

  // `path` is an optional URL path which will be sent in any request to

  //
  // Only one condition of a given type is allowed.
  optional string type = 1;

  // status of the condition, one of True, False, Unknown.
  // Approved, Denied, and Failed conditions may not be "False" or "Unknown".
  optional string status = 6;

  // reason indicates a brief reason for the request state
  // +optional
  optional string reason = 2;

        scheme: str,
        scheme_name: Optional[str] = None,
        description: Optional[str] = None,
        auto_error: bool = True,
    ):
        self.model = HTTPBaseModel(scheme=scheme, description=description)
        self.scheme_name = scheme_name or self.__class__.__name__
        self.auto_error = auto_error

    async def __call__(
        self, request: Request
    ) -> Optional[HTTPAuthorizationCredentials]:

    scope: Optional string. Several scopes (each one a string) separated by spaces. E.g.
        "items:read items:write users:read profile openid"
    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)

    ```

#### Using `Union` or `Optional`

If you are using a Python version below 3.10, here's a tip from my very **subjective** point of view:

* 🚨 Avoid using `Optional[SomeType]`
* Instead ✨ **use `Union[SomeType, None]`** ✨.

        return versionRange.isSelectedVersionKnown(this);
    }

    @Override
    public void setOptional(boolean optional) {
        this.optional = optional;
    }

            @Override
            public <T> Optional<T> lookupOptional(Class<T> type) {
                try {
                    return Optional.of(injector.getInstance(type));
                } catch (DIException e) {
                    return Optional.empty();
                }
            }

            @Override
            public <T> Optional<T> lookupOptional(Class<T> type, String name) {

    ```

#### `Union` oder `Optional` verwenden?

Wenn Sie eine Python-Version unterhalb 3.10 verwenden, hier ist mein sehr **subjektiver** Standpunkt dazu:

* 🚨 Vermeiden Sie `Optional[SomeType]`
* Stattdessen ✨ **verwenden Sie `Union[SomeType, None]`** ✨.