<p>
In its most basic form an interface specifies a (possibly empty) list of methods.
The type set defined by such an interface is the set of types which implement all of
those methods, and the corresponding <a href="#Method_sets">method set</a> consists
exactly of the methods specified by the interface.
Interfaces whose type sets can be defined entirely by a list of methods are called
<i>basic interfaces.</i>
</p>

<pre>

#### client-go:

* The `DefaultFeatureGate` package variable now only exposes readonly feature gate methods. Methods for mutating feature gates have moved into a `MutableFeatureGate` interface and are accessible via the `DefaultMutableFeatureGate` package variable. Only top-level commands and options setup should access `DefaultMutableFeatureGate`. ([#7130...

- Changed NodeToStatusMap from a map to a struct and exposed methods to access the entries. Added absentNodesStatus, which informs the status of nodes that are absent in the map. For developers of out-of-tree PostFilter plugins, ensure to update the usage of NodeToStatusMap. Additionally, NodeToStatusMap should eventually...

Before updating to 1.9, you are strongly recommended to back up your etcd data. Consult the installation procedure you are using (kargo, kops, kube-up, kube-aws, kubeadm etc) for specific advice.

- CEL authorizer checks no longer raise runtime errors. Calls to "check" will always return a decision object and the authorization error (if any) can be accessed within expressions using the new decision methods "errored" and "error". ([#118804](https://github.com/kubernetes/kubernetes/pull/118804), [@benluddy](https://github.com/benluddy)) [SIG API Machinery]

pkg go/build/constraint, type Expr interface, Eval(func(string) bool) bool
pkg go/build/constraint, type Expr interface, String() string
pkg go/build/constraint, type Expr interface, unexported methods
pkg go/build/constraint, type NotExpr struct
pkg go/build/constraint, type NotExpr struct, X Expr
pkg go/build/constraint, type OrExpr struct
pkg go/build/constraint, type OrExpr struct, X Expr

- Added name validation for dynamic client methods in client-go ([#75072](https://github.com/kubernetes/kubernetes/pull/75072), [@lblackstone](https://github.com/lblackstone))

checks for `err == ErrWaitTimeout`, or compare specifically to context errors as needed. A future release will make the `ErrWaitTimeout` error private and callers must use `Interrupted()` instead. If you are returning `ErrWaitTimeout` from your own methods, switch to creating a location specific `cause err` and pass it to the new method `wait.ErrorInterrupted(cause) error` which will ensure `Interrupted()` returns true for your loop. 
  
  The `wait.NewExponentialBackoffManager` and `wa...

* Fixes [#49418](https://github.com/kubernetes/kubernetes/pull/49418) where kube-controller-manager can panic on volume.CanSupport methods and enter a crash loop. ([#49420](https://github.com/kubernetes/kubernetes/pull/49420), [@gnufied](https://github.com/gnufied))