Added SuppressWarnings annotation

src/main/java/de/epiceric/shopchest/external/listeners/PlotSquaredListener.java

@@ -20,6 +20,7 @@ import org.bukkit.event.Listener;
 
 import java.util.Set;
 
+@SuppressWarnings("UnstableApiUsage")
 public class PlotSquaredListener implements Listener {
     private final ShopChest plugin;
 
@@ -120,4 +121,4 @@ public class PlotSquaredListener implements Listener {
         }
         return false;
     }
-}
+}