Add annotation.

src/main/java/com/raoulvdberge/refinedstorage/api/autocrafting/ICraftingManager.java

@@ -28,6 +28,7 @@ public interface ICraftingManager {
      * @param id the id
      * @return the task, or null if no task was found for the given id
      */
+    @Nullable
     ICraftingTask getTask(UUID id);
 
     /**

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/autocrafting/CraftingManager.java

@@ -50,6 +50,7 @@ public class CraftingManager implements ICraftingManager {
     }
 
     @Override
+    @Nullable
     public ICraftingTask getTask(UUID id) {
         return tasks.get(id);
     }