Switch from LockedState to Mutex for NotificationCenter.registrar

Author: cthielen

Sources/FoundationEssentials/NotificationCenter/NotificationCenter.swift

@@ -20,6 +20,8 @@ extension NotificationCenter {
 }
 #endif
 
+internal import Synchronization
+
 #if !FOUNDATION_FRAMEWORK
 
 // Dictionary storage with automatic key generation
@@ -75,11 +77,11 @@ private struct MessageBox {
 }
 
 open class NotificationCenter: @unchecked Sendable {
-    private var registrar: LockedState<[String? /* Notification name */: [ObjectIdentifier? /* object */ : AutoDictionary<@Sendable (MessageBox) -> Void>]]>
+    private let registrar: Mutex<[String? /* Notification name */: [ObjectIdentifier? /* object */ : AutoDictionary<@Sendable (MessageBox) -> Void>]]>
     internal lazy var _actorQueueManager = _NotificationCenterActorQueueManager()
 
     public required init() {
-        registrar = LockedState(initialState: [:])
+        registrar = .init([:])
     }
 
     open class var `default`: NotificationCenter {