[HttpKernel] Fix creating ReflectionMethod with only one argument

Author: alexandre-daubois

src/Symfony/Component/HttpKernel/Event/ControllerEvent.php

@@ -70,7 +70,7 @@ public function setController(callable $controller, ?array $attributes = null):
         if (\is_array($controller) && method_exists(...$controller)) {
             $this->controllerReflector = new \ReflectionMethod(...$controller);
         } elseif (\is_string($controller) && str_contains($controller, '::')) {
-            $this->controllerReflector = new \ReflectionMethod($controller);
+            $this->controllerReflector = new \ReflectionMethod(...explode('::', $controller, 2));
         } else {
             $this->controllerReflector = new \ReflectionFunction($controller(...));
         }