Add missing return type for CacheWarmer::isOptional()

Author: Kai Eichinger

CHANGELOG.md

@@ -1,3 +1,9 @@
+2.7.1
+=====
+
+*   (improvement) Add missing return type for `CacheWarmer::isOptional()`.
+
+
 2.7.0
 =====
 

src/Cache/CacheWarmer.php

@@ -104,7 +104,7 @@ public function fillCache (?SymfonyStyle $io) : void
     /**
      * @inheritdoc
      */
-    public function isOptional ()
+    public function isOptional () : bool
     {
         return true;
     }