Refactor: Existing handler to using constructor of superclass

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/check_nick/CheckUsernameHandler.java

@@ -8,7 +8,6 @@ import java.util.Optional;
 
 /** Handles {@link CheckUsernameRequest}s to check whether a username is available. */
 public class CheckUsernameHandler extends CommandHandler<CheckUsernameRequest> {
-    private final ResponseDispatcher responseDispatcher;
     private final UserRegistry userRegistry;
 
     /**
@@ -18,7 +17,7 @@ public class CheckUsernameHandler extends CommandHandler<CheckUsernameRequest> {
      * @param userRegistry the registry used to look up existing users
      */
     public CheckUsernameHandler(ResponseDispatcher responseDispatcher, UserRegistry userRegistry) {
-        this.responseDispatcher = responseDispatcher;
+        super(responseDispatcher);
         this.userRegistry = userRegistry;
     }
 

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/login/LoginHandler.java

@@ -14,7 +14,6 @@ import java.util.Optional;
  * already
  */
 public class LoginHandler extends CommandHandler<LoginRequest> {
-    private final ResponseDispatcher responseDispatcher;
     private final UserRegistry userRegistry;
     private final UserFactory userFactory;
 
@@ -25,7 +24,7 @@ public class LoginHandler extends CommandHandler<LoginRequest> {
      * @param userRegistry the registry used to look up existing users and create the new one
      */
     public LoginHandler(ResponseDispatcher responseDispatcher, UserRegistry userRegistry) {
-        this.responseDispatcher = responseDispatcher;
+        super(responseDispatcher);
         this.userRegistry = userRegistry;
         this.userFactory = new UserFactory(userRegistry);
     }

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/logout/LogoutHandler.java

@@ -8,7 +8,6 @@ import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatch
 
 /** Handles {@link LogoutRequest} to logout connected user. */
 public class LogoutHandler extends CommandHandler<LogoutRequest> {
-    private final ResponseDispatcher responseDispatcher;
     private final UserRegistry userRegistry;
 
     /**
@@ -18,7 +17,7 @@ public class LogoutHandler extends CommandHandler<LogoutRequest> {
      * @param userRegistry registry responsible for tracking connected user sessions
      */
     public LogoutHandler(ResponseDispatcher responseDispatcher, UserRegistry userRegistry) {
-        this.responseDispatcher = responseDispatcher;
+        super(responseDispatcher);
         this.userRegistry = userRegistry;
     }
 

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/ping/PingHandler.java

@@ -6,7 +6,6 @@ import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatch
 
 /** Handler for {@link PingRequest}. */
 public class PingHandler extends CommandHandler<PingRequest> {
-    private final ResponseDispatcher responseDispatcher;
 
     /**
      * Create a new PingHandler to execute {@link PingRequest}s
@@ -14,7 +13,7 @@ public class PingHandler extends CommandHandler<PingRequest> {
      * @param responseDispatcher dispatcher used to send responses back to clients
      */
     public PingHandler(ResponseDispatcher responseDispatcher) {
-        this.responseDispatcher = responseDispatcher;
+        super(responseDispatcher);
     }
 
     /**