Merge pull request #143 from javaevolved/copilot/update-java-version-guarded-patterns

Fix guarded-patterns: replace instanceof pattern matching with Java 8 compatible old code

Author: brunoborges

content/language/guarded-patterns.yaml

@@ -10,7 +10,8 @@ modernLabel: "Java 21+"
 oldApproach: "Nested if"
 modernApproach: "when Clause"
 oldCode: |-
-  if (shape instanceof Circle c) {
+  if (shape instanceof Circle) {
+      Circle c = (Circle) shape;
       if (c.radius() > 10) {
           return "large circle";
       } else {