- `ValidatingAdmissionPolicy` now preserves types of composition variables, and raises type-related errors early. ([#121001](https://github.com/kubernetes/kubernetes/pull/121001), [@jiahuif](https://github.com/jiahuif))

type Mutex struct         { /* Mutex fields */ }
func (m *Mutex) Lock()    { /* Lock implementation */ }
func (m *Mutex) Unlock()  { /* Unlock implementation */ }

// NewMutex has the same composition as Mutex but its method set is empty.
type NewMutex Mutex

// The method set of PtrMutex's underlying type *Mutex remains unchanged,
// but the method set of PtrMutex is empty.
type PtrMutex *Mutex