use List interface instead of ArrayList implementation in several places

src/main/java/eu/crushedpixel/replaymod/assets/CustomObjectRepository.java

@@ -1,18 +1,24 @@
 package eu.crushedpixel.replaymod.assets;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
+import lombok.Getter;
 
 import java.util.ArrayList;
+import java.util.List;
 
-@Data
-@AllArgsConstructor
 public class CustomObjectRepository {
 
     public CustomObjectRepository() {
         this.objects = new ArrayList<CustomImageObject>();
     }
+    public CustomObjectRepository(List<CustomImageObject> objects) {
+        setObjects(objects);
+    }
 
+    public void setObjects(List<CustomImageObject> objects) {
+        this.objects = new ArrayList<CustomImageObject>(objects);
+    }
+
+    @Getter
     private ArrayList<CustomImageObject> objects;
 
 }

src/main/java/eu/crushedpixel/replaymod/gui/GuiObjectManager.java

@@ -26,7 +26,6 @@ import org.lwjgl.util.Point;
 import java.awt.*;
 import java.io.File;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 
@@ -363,7 +362,7 @@ public class GuiObjectManager extends GuiScreen {
     }
 
     private void saveOnQuit() {
-        ArrayList<CustomImageObject> objects = objectList.getCopyOfElements();
+        List<CustomImageObject> objects = objectList.getCopyOfElements();
         ReplayHandler.setCustomImageObjects(objects);
 
         if(objects.size() > 0) {

src/main/java/eu/crushedpixel/replaymod/gui/elements/GuiEntryList.java

@@ -150,7 +150,7 @@ public class GuiEntryList<T extends GuiEntryListEntry> extends GuiAdvancedTextFi
         fireSelectionChangeEvent();
     }
 
-    public ArrayList<T> getCopyOfElements() {
+    public List<T> getCopyOfElements() {
         return new ArrayList<T>(elements);
     }
 

src/main/java/eu/crushedpixel/replaymod/replay/ReplayHandler.java

@@ -617,8 +617,8 @@ public class ReplayHandler {
         customImageObjects.getObjects().add(object);
     }
 
-    public static void setCustomImageObjects(ArrayList<CustomImageObject> objects) {
-        customImageObjects.setObjects(objects);
+    public static void setCustomImageObjects(List<CustomImageObject> objects) {
+        customImageObjects.setObjects(new ArrayList<CustomImageObject>(objects));
     }
 
     public static void fireKeyframesModifyEvent() {