For a standard Kubernetes deployment, both CA and discovery will use JWT authentication, with a token automatically
[generated and rotated by Kubernetes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/#service-account-token-volume-projection).

For discovery, the JWT token will be read directly from a file and sent as is. For CA, this logic is a bit more complex,

  // if a fstype is defined and the volume's access mode contains ReadWriteOnce.
  //
  // +optional
  optional string fsGroupPolicy = 5;

  // tokenRequests indicates the CSI driver needs pods' service account
  // tokens it is mounting volume for to do necessary authentication. Kubelet
  // will pass the tokens in VolumeContext in the CSI NodePublishVolume calls.

// +protobuf.options.(gogoproto.goproto_stringer)=false
message ExtraValue {
  // items, if empty, will result in an empty slice

  repeated string items = 1;
}

// TokenRequest requests a token for a given service account.
message TokenRequest {
  // Standard object's metadata.
  // More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
  // +optional

  optional int32 replicas = 1;

  // selector is a label query over pods that should match the replicas count. More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/
  // +optional
  // +mapType=atomic
  map<string, string> selector = 2;

  // label selector for pods that should match the replicas count. This is a serializated
  // version of both map-based and more expressive set-based selectors. This is done to

  // if a fstype is defined and the volume's access mode contains ReadWriteOnce.
  //
  // +optional
  optional string fsGroupPolicy = 5;

  // tokenRequests indicates the CSI driver needs pods' service account
  // tokens it is mounting volume for to do necessary authentication. Kubelet
  // will pass the tokens in VolumeContext in the CSI NodePublishVolume calls.

  // Pods are only limited to this list if this service account has a "kubernetes.io/enforce-mountable-secrets" annotation set to "true".
  // This field should not be used to find auto-generated service account token secrets for use outside of pods.
  // Instead, tokens can be requested directly using the TokenRequest API, or service account token secrets can be manually created.

  // the job controller hasn't yet accounted for in the status counters.
  //
  // The job controller creates pods with a finalizer. When a pod terminates
  // (succeeded or failed), the controller does three steps to account for it
  // in the job status:
  //
  // 1. Add the pod UID to the arrays in this field.
  // 2. Remove the pod finalizer.
  // 3. Remove the pod UID from the arrays while increasing the corresponding

  // 'request' - Attributes of the admission request(/pkg/apis/admission/types.go#AdmissionRequest).
  // 'authorizer' - A CEL Authorizer. May be used to perform authorization checks for the principal (user or service account) of the request.
  //   See https://pkg.go.dev/k8s.io/apiserver/pkg/cel/library#Authz
  // 'authorizer.requestResource' - A CEL ResourceCheck constructed from the 'authorizer' and configured with the
  //   request resource.

  // 'request' - Attributes of the admission request(/pkg/apis/admission/types.go#AdmissionRequest).
  // 'authorizer' - A CEL Authorizer. May be used to perform authorization checks for the principal (user or service account) of the request.
  //   See https://pkg.go.dev/k8s.io/apiserver/pkg/cel/library#Authz
  // 'authorizer.requestResource' - A CEL ResourceCheck constructed from the 'authorizer' and configured with the
  //   request resource.

// how this struct is updated on heartbeats and can guide customized reporter implementations.
message EventSeries {
  // count is the number of occurrences in this series up to the last heartbeat time.
  optional int32 count = 1;

  // lastObservedTime is the time when last Event from the series was seen before last heartbeat.