- 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))

which have no other owners are deleted from the live object, or reset to their default value if they have one. Safe ownership transfers, such as the transfer of a `replicas` field from a user to an HPA without resetting to the default value are documented in [Transferring Ownership](https://kubernetes.io/docs/reference/using-api/api-concepts/#transferring-ownership) ([#92661](https://github.com/kubernetes/kubernetes/pull/92661), [@jpbetz](https://github.com/jpbetz)) [SIG API Machinery, CLI, Cloud...

### Other notable changes

### Other notable changes

* Pod affinity `nodeSelectorTerm.matchExpressions` may now be empty, and works as previously documented: nil or empty `matchExpressions` matches no objects in scheduler. ([#62448](https://github.com/kubernetes/kubernetes/pull/62448), [@k82cn](https://github.com/k82cn))

    * PR [#1862](https://github.com/tiangolo/fastapi/pull/1862).
* In `encoders.jsonable_encoder` remove parameter `sqlalchemy_safe`.
    * It was an early hack to allow returning SQLAlchemy models, but it was never documented, and the recommended way is using Pydantic's `orm_mode` as described in the tutorial: [SQL (Relational) Databases](https://fastapi.tiangolo.com/tutorial/sql-databases/).
    * PR [#1864](https://github.com/tiangolo/fastapi/pull/1864).

- Using `--log-file` is known to be problematic in 1.15. This presents as things being logged multiple times to the same file. The behaviour and details of this issue, as well as some preliminary attempts at fixing it are documented [here](https://github.com/kubernetes/kubernetes/issues/78734#issuecomment-501372131)

## Urgent Upgrade Notes

### (No, really, you MUST read this before you upgrade)

#### API Machinery

- 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]

* For x-kubernetes-list-type=set a scalar or atomic item type is now required, as documented. Persisted, invalid data is tolerated. ([#85385](https://github.com/kubernetes/kubernetes/pull/85385), [@sttts](https://github.com/sttts))

	g()
}
</pre>


<h3 id="Bootstrapping">Bootstrapping</h3>

<p>
Current implementations provide several built-in functions useful during
bootstrapping. These functions are documented for completeness but are not
guaranteed to stay in the language. They do not return a result.
</p>

<pre class="grammar">
Function   Behavior