Code clean up and test fixes

executor-base/src/main/java/ch/unisg/executorbase/Task.java

@@ -6,7 +6,7 @@ import lombok.Setter;
 public class Task {
 
     @Getter
-    private String taskID;
+    private final String taskID;
 
     @Getter
     @Setter
@@ -15,7 +15,7 @@ public class Task {
     // TODO maybe create a value object for inputData so we can make sure it is in the right
     // format.
     @Getter
-    private String inputData;
+    private final String inputData;
 
     public Task(String taskID, String inputData) {
         this.taskID = taskID;

executor-base/src/main/java/ch/unisg/executorbase/services/ExecuteTaskServiceBase.java

@@ -9,7 +9,7 @@ import ch.unisg.executorbase.Task;
 
 public abstract class ExecuteTaskServiceBase implements ExecuteTaskServiceInterface {
 
-    private Logger logger = Logger.getLogger(ExecuteTaskServiceBase.class.getName());
+    private final Logger logger = Logger.getLogger(ExecuteTaskServiceBase.class.getName());
 
     @Autowired
     private Executor executor;

executor-base/src/main/java/ch/unisg/executorbase/services/ExecutionFinishedService.java

@@ -18,7 +18,7 @@ public class ExecutionFinishedService {
     @Value("${roster.uri}")
     private String rosterUri;
 
-    private Logger logger = Logger.getLogger(ExecutionFinishedService.class.getName());
+    private final Logger logger = Logger.getLogger(ExecutionFinishedService.class.getName());
 
     /**
     *   Publishes the execution finished event