* if kube-apiserver is started with `--storage-backend=etcd2`, the media type `application/json` is used. ([#43122](https://github.com/kubernetes/kubernetes/pull/43122), [@liggitt](https://github.com/liggitt))
* API fields that previously serialized null arrays as `null` and empty arrays as `[]` no longer distinguish between those values and always output `[]` when serializing to JSON. ([#43422](https://github.com/kubernetes/kubernetes/pull/43422), [@liggitt](https://github.com/liggitt))

   ([#122276](https://github.com/kubernetes/kubernetes/pull/122276), [@pohly](https://github.com/pohly))
- Added a CBOR implementation of `runtime.Serializer`. Until CBOR graduates to Alpha, API servers will refuse to start if configured with CBOR support. ([#122881](https://github.com/kubernetes/kubernetes/pull/122881), [@benluddy](https://github.com/benluddy))

- Ipvs: only attempt setting of sysctlconnreuse on supported kernels ([#88541](https://github.com/kubernetes/kubernetes/pull/88541), [@cmluciano](https://github.com/cmluciano)) [SIG Network]
- Jsonpath support in kubectl / client-go serializes complex types (maps / slices / structs) as json instead of Go-syntax. ([#89660](https://github.com/kubernetes/kubernetes/pull/89660), [@pjferrell](https://github.com/pjferrell)) [SIG API Machinery, CLI and Cluster Lifecycle]

    <sub-class-of type="application/java-archive"/>
    <glob pattern="*.war"/>
  </mime-type>

  <mime-type type="application/x-tika-unix-dump"/>

  <mime-type type="application/java-serialized-object">
    <glob pattern="*.ser"/>
  </mime-type>

  <mime-type type="application/javascript">
    <alias type="application/x-javascript"/>
    <alias type="text/javascript"/>