API fields previously capable of storing and returning either `[]` and `null` via JSON API requests (for example, the Endpoints `subsets` field)
can now store only `null` when created using the protobuf content-type or stored in etcd using protobuf serialization (the default in 1.6).

### API Change

- Protobuf serialization of metav1.MicroTime timestamps (used in `Lease` and `Event` API objects) has been corrected to truncate to microsecond precision, to match the documented behavior and JSON/YAML serialization. Any existing persisted data is truncated to microsecond when read from etcd. ([#111936](https://github.com/kubernetes/kubernetes/pull/111936), [@haoruan](https://github.com/haoruan)) [SIG API Machinery]

  - The /swagger.json and /swagger-2.0.0.pb-v1 schema documents, deprecated since v1.10, have been removed in favor of `/openapi/v2` ([#73148](https://github.com/kubernetes/kubernetes/pull/73148), [@liggitt](https://github.com/liggitt))

- kube-controller-manager
  - The deprecated `--insecure-experimental-approve-all-kubelet-csrs-for-group` flag has been removed.
- kubelet
  - The deprecated `--google-json-key` flag has been removed. Remove the `--google-json-key` flag from kubelet invocations before upgrading. ([#69354](https://github.com/kubernetes/kubernetes/pull/69354), [@yujuhong](https://github.com/yujuhong))

## Dependencies

### Added
_Nothing has changed._

### Changed
- github.com/evanphx/json-patch: [v5.6.0+incompatible → v4.12.0+incompatible](https://github.com/evanphx/json-patch/compare/v5.6.0...v4.12.0)
- github.com/google/cel-go: [v0.16.0 → v0.16.1](https://github.com/google/cel-go/compare/v0.16.0...v0.16.1)

### Removed
_Nothing has changed._

- github.com/envoyproxy/protoc-gen-validate: [v0.9.1 → v1.0.2](https://github.com/envoyproxy/protoc-gen-validate/compare/v0.9.1...v1.0.2)
- github.com/evanphx/json-patch: [v5.6.0+incompatible → v4.12.0+incompatible](https://github.com/evanphx/json-patch/compare/v5.6.0...v4.12.0)
- github.com/fsnotify/fsnotify: [v1.6.0 → v1.7.0](https://github.com/fsnotify/fsnotify/compare/v1.6.0...v1.7.0)

## Dependencies

### Added
_Nothing has changed._

### Changed
- github.com/evanphx/json-patch: [162e562 → v4.9.0+incompatible](https://github.com/evanphx/json-patch/compare/162e562...v4.9.0)

### Removed
- github.com/jessevdk/go-flags: [v1.4.0](https://github.com/jessevdk/go-flags/tree/v1.4.0)



# v1.18.8

- the ability to rollback to etcd2 can be preserved by setting the storage media type flag on `kube-apiserver`

  ```
  --storage-media-type application/json
  ```

  to continue to use `application/json` as the storage media type which can be changed to
  `application/vnd.kubernetes.protobuf` at a later time.

## Major updates and release themes

* Fix aggressive VM calls for Azure VMSS ([#83102](https://github.com/kubernetes/kubernetes/pull/83102), [@feiskyer](https://github.com/feiskyer))

  // defaultMode is optional: mode bits used to set permissions on created files by default.
  // Must be an octal value between 0000 and 0777 or a decimal value between 0 and 511.
  // YAML accepts both octal and decimal values, JSON requires decimal values for mode bits.
  // Defaults to 0644.
  // Directories within the path are not affected by this setting.
  // This might be in conflict with other options that affect the file