fix(ecs-gestalt): Migrate Components to gestalt's Components. (#8)

Ref: MovingBlocks/Terasology#4753

Co-authored-by: Michael Pollind <mpollind@gmail.com>
Co-authored-by: Tobias Nett <skaldarnar@googlemail.com>

src/main/java/org/terasology/notifications/model/NotificationComponent.java

@@ -1,9 +1,9 @@
-// Copyright 2020 The Terasology Foundation
+// Copyright 2021 The Terasology Foundation
 // SPDX-License-Identifier: Apache-2.0
 
 package org.terasology.notifications.model;
 
-import org.terasology.engine.entitySystem.Component;
+import org.terasology.gestalt.entitysystem.component.Component;
 import org.terasology.notifications.events.ExpireNotificationEvent;
 import org.terasology.notifications.events.ShowNotificationEvent;
 
@@ -15,7 +15,7 @@
  * <p>
  * Please use {@link ShowNotificationEvent} and {@link ExpireNotificationEvent} to modify the displayed notifications.
  */
-public class NotificationComponent implements Component {
+public class NotificationComponent implements Component<NotificationComponent> {
     /**
      * The ordered list of notifications to show in the notification overlay.
      */
@@ -24,4 +24,10 @@ public class NotificationComponent implements Component {
     public NotificationComponent() {
         notifications = new ArrayList<>();
     }
+
+    @Override
+    public void copyFrom(NotificationComponent other) {
+        notifications.clear();
+        notifications.addAll(other.notifications);
+    }
 }

src/main/java/org/terasology/notifications/ui/NotificationAreaOverlay.java

@@ -14,6 +14,7 @@
 import org.terasology.nui.databinding.ReadOnlyBinding;
 import org.terasology.nui.widgets.UIList;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
@@ -43,9 +44,10 @@ public void initialise() {
             @Override
             public List<TimedNotification> get() {
                 EntityRef client = localPlayer.getClientEntity();
-                return Optional.ofNullable(client.getComponent(NotificationComponent.class))
+                List<TimedNotification> timedNotifications = Optional.ofNullable(client.getComponent(NotificationComponent.class))
                         .map(component -> component.notifications)
                         .orElse(Collections.emptyList());
+                return timedNotifications;
             }
         });
     }