Remove StaticReflectionService

Additionally, implementations of ReflectionService may no longer return
null for calls to getClass().

UPGRADE.md

@@ -8,6 +8,16 @@ awareness about deprecated code.
 
 # Upgrade to 4.0
 
+## BC Break: Removed `StaticReflectionService`
+
+The class `Doctrine\Persistence\Mapping\StaticReflectionService` is removed
+without replacement.
+
+## BC Break: Narrowed `ReflectionService::getClass()` return type
+
+The return type of `ReflectionService::getClass()` has been narrowed so that
+`null` is no longer a valid return value.
+
 ## BC Break: Added `ObjectManager::isUninitializedObject()`
 
 Classes implementing `Doctrine\Persistence\ObjectManager` must implement this

src/Persistence/Mapping/ReflectionService.php

@@ -42,11 +42,11 @@ public function getClassNamespace(string $class): string;
      *
      * @psalm-param class-string<T> $class
      *
-     * @psalm-return ReflectionClass<T>|null
+     * @psalm-return ReflectionClass<T>
      *
      * @template T of object
      */
-    public function getClass(string $class): ReflectionClass|null;
+    public function getClass(string $class): ReflectionClass;
 
     /**
      * Returns an accessible property (setAccessible(true)) or null.