Remove useless code

Former-commit-id: ef4e7e9

src/main/java/org/maxgamer/quickshop/Shop/ContainerShop.java

@@ -68,7 +68,6 @@ public class ContainerShop implements Shop {
   private double price;
   private ShopType shopType;
   private boolean unlimited;
-  private boolean isDeleted;
 
   private ContainerShop(@NotNull ContainerShop s) {
     this.displayItem = s.displayItem;
@@ -399,7 +398,6 @@ public void delete(boolean fromMemory) {
     if (isLoaded) {
       this.onUnload();
     }
-    isDeleted=true;
     // Delete the display item
     if (this.getDisplayItem() != null) {
       this.getDisplayItem().remove();
@@ -877,11 +875,6 @@ public boolean isValid() {
     return Util.canBeShop(this.getLocation().getBlock());
   }
 
-  @Override
-  public boolean isDeleted() {
-    return isDeleted;
-  }
-
   @Override
   public @Nullable DisplayItem getDisplay() {
     return this.displayItem;

src/main/java/org/maxgamer/quickshop/Shop/Shop.java

@@ -303,12 +303,6 @@ public interface Shop {
    */
   boolean isValid();
 
-  /**
-   * Shop is deleted
-   *
-   * @return true if deleted
-   */
-  boolean isDeleted();
 
   /**
    * Get the shop display entity

src/main/java/org/maxgamer/quickshop/Shop/VirtualDisplayItem.java

@@ -49,7 +49,6 @@ public class VirtualDisplayItem extends DisplayItem {
 
     private static ProtocolManager protocolManager = ProtocolLibrary.getProtocolManager();
     private volatile boolean isDisplay;
-    private volatile boolean isLoaded;
     //counter for ensuring ID is unique
     private static final AtomicInteger counter = new AtomicInteger(0);
     //server main version (1_13_R2->13)
@@ -92,11 +91,6 @@ public void onPacketSending(PacketEvent event) {
                     //is really full chunk data
                     boolean isFull = event.getPacket().getBooleans().read(0);
 
-                    //if shop has deleted, unregister myself to ensure will be collected by GC
-                    if (!shop.isDeleted()) {
-                        unload();
-                        return;
-                    }
                     if (!shop.isLoaded() || !isDisplay || !isFull || !Util.isLoaded(shop.getLocation())) {
                         return;
                     }
@@ -105,7 +99,6 @@ public void onPacketSending(PacketEvent event) {
                     //chunk z
                     int z = event.getPacket().getIntegers().read(1);
 
-
                     World world = shop.getLocation().getWorld();
                     Chunk chunk = shop.getLocation().getChunk();
                     if (world.getName().equals(event.getPlayer().getWorld().getName())