annotate initialize method @NotNull

common/addons/biome-provider-image/src/main/java/com/dfsek/terra/addons/biome/image/ImageBiomeProviderAddon.java

@@ -23,13 +23,15 @@ import com.dfsek.terra.api.util.reflection.TypeKey;
 import com.dfsek.terra.api.world.biome.Biome;
 import com.dfsek.terra.api.world.biome.generation.BiomeProvider;
 
+import org.jetbrains.annotations.NotNull;
+
 
 public class ImageBiomeProviderAddon implements MonadAddonInitializer {
     public static final TypeKey<Supplier<ObjectTemplate<BiomeProvider>>> PROVIDER_REGISTRY_KEY = new TypeKey<>() {
     };
     
     @Override
-    public Monad<?, Init<?>> initialize() {
+    public @NotNull Monad<?, Init<?>> initialize() {
         return Do.with(
                 Get.eventManager().map(eventManager -> eventManager.getHandler(FunctionalEventHandler.class)),
                 Get.addon(),