make services final in controller

backend/secret-archive-rest/src/main/java/cz/fi/muni/pa165/seminar4/group7/controller/AgentController.java

@@ -33,9 +33,9 @@ import cz.fi.muni.pa165.seminar4.group7.facade.AgentFacade;
 @RequestMapping(value = "/agents")
 public class AgentController {
 
-    private AgentService agentService;
-    private AgentFacade agentFacade;
-    private BeanMappingServiceImpl beanMappingService;
+    private final AgentService agentService;
+    private final AgentFacade agentFacade;
+    private final BeanMappingServiceImpl beanMappingService;
     
 
     @Autowired
@@ -48,7 +48,7 @@ public class AgentController {
 
     @GetMapping()
     public List<AgentDTO> getAllAgents(
-        // Coma separated list of skills
+        // Comma separated list of skills
         @RequestParam(value = "skills", required = false) String skills,
         @RequestParam(value = "country", required = false) String countryId
     ) {