Add RegionSkins

BauSystem/BauSystem_Main/src/de/steamwar/bausystem/region/RegionSystem.java

@@ -19,8 +19,10 @@
 
 package de.steamwar.bausystem.region;
 
+import lombok.NonNull;
 import org.bukkit.Location;
 
+import javax.annotation.CheckReturnValue;
 import java.lang.reflect.InvocationTargetException;
 import java.util.Optional;
 import java.util.UUID;
@@ -33,11 +35,16 @@ public interface RegionSystem {
     void load();
     void save();
 
+    @NonNull
     Region getGlobalRegion();
 
-    Region get(Location location);
-    Optional<Region> getRegion(UUID id);
+    @NonNull
+    Region get(@NonNull Location location);
 
+    @CheckReturnValue
+    Optional<Region> getRegion(@NonNull UUID id);
+
+    @NonNull
     Stream<Region> getRegions();
 
     boolean isModular();