refactor(welcome): update getRoles method signature

src/main/java/de/szut/lf8_starter/security/KeycloakSecurityConfig.java

@@ -84,8 +84,8 @@ class KeycloakSecurityConfig {
             List<GrantedAuthority> grantedAuthorities = new ArrayList<>();
 
             Map<String, Object> realmAccess = jwt.getClaim(REALM_ACCESS_CLAIM);
-            if (realmAccess != null && realmAccess.containsKey("roles")) {
+            if (realmAccess != null && realmAccess.containsKey(ROLES_CLAIM)) {
-                List<String> roles = (List<String>) realmAccess.get("roles");
+                List<String> roles = (List<String>) realmAccess.get(ROLES_CLAIM);
                 for (String role : roles) {
                     grantedAuthorities.add(new SimpleGrantedAuthority("ROLE_" + role));
                 }

src/main/java/de/szut/lf8_starter/welcome/WelcomeController.java

@@ -3,12 +3,12 @@ package de.szut.lf8_starter.welcome;
 
 
 import org.springframework.http.ResponseEntity;
-import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.security.core.Authentication;
+import org.springframework.security.core.GrantedAuthority;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 
-import java.security.Principal;
+import java.util.Collection;
 
 @RestController
 public class WelcomeController {
@@ -19,7 +19,7 @@ public class WelcomeController {
     }
 
     @GetMapping("/roles")
-    public ResponseEntity<?> getRoles(Authentication authentication) {
+    public ResponseEntity<Collection<? extends GrantedAuthority>> getRoles(Authentication authentication) {
         return ResponseEntity.ok(authentication.getAuthorities());
     }