doesn't include null RHL in the handler map

src/main/java/com/gregtechceu/gtceu/api/capability/recipe/IRecipeCapabilityHolder.java

@@ -28,6 +28,7 @@ default List<IRecipeHandler<?>> getCapabilitiesFlat(IO io, RecipeCapability<?> c
     }
 
     default void addHandlerList(RecipeHandlerList handler) {
+        if (handler == RecipeHandlerList.NO_DATA) return;
         IO io = handler.getHandlerIO();
         getCapabilitiesProxy().computeIfAbsent(io, i -> new ArrayList<>()).add(handler);
         var inner = getCapabilitiesFlat().computeIfAbsent(io, i -> new Reference2ObjectOpenHashMap<>());

src/main/java/com/gregtechceu/gtceu/api/machine/feature/multiblock/IMultiPart.java

@@ -64,6 +64,7 @@ default boolean canShared() {
     /**
      * Get all available traits for recipe logic.
      */
+    @Nullable
     RecipeHandlerList getRecipeHandlers();
 
     /**

src/main/java/com/gregtechceu/gtceu/api/machine/multiblock/part/MultiblockPartMachine.java

@@ -1,6 +1,5 @@
 package com.gregtechceu.gtceu.api.machine.multiblock.part;
 
-import com.gregtechceu.gtceu.api.capability.recipe.IO;
 import com.gregtechceu.gtceu.api.capability.recipe.IRecipeHandler;
 import com.gregtechceu.gtceu.api.machine.IMachineBlockEntity;
 import com.gregtechceu.gtceu.api.machine.MetaMachine;
@@ -20,6 +19,7 @@
 
 import it.unimi.dsi.fastutil.objects.ObjectOpenHashSet;
 import it.unimi.dsi.fastutil.objects.ReferenceLinkedOpenHashSet;
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.annotations.UnmodifiableView;
 
 import java.util.Collections;
@@ -92,14 +92,15 @@ public SortedSet<IMultiController> getControllers() {
         return Collections.unmodifiableSortedSet(controllers);
     }
 
+    @Nullable
     public RecipeHandlerList getRecipeHandlers() {
         if (handlerList == null) {
             var a = traits.stream()
                     .filter(IRecipeHandlerTrait.class::isInstance)
                     .map(IRecipeHandlerTrait.class::cast)
                     .toList();
             if (a.isEmpty()) {
-                handlerList = new RecipeHandlerList(IO.NONE);
+                handlerList = RecipeHandlerList.NO_DATA;
                 return handlerList;
             }
             handlerList = new RecipeHandlerList(a.get(0).getHandlerIO());

src/main/java/com/gregtechceu/gtceu/api/machine/trait/RecipeHandlerList.java

@@ -21,6 +21,8 @@
 
 public class RecipeHandlerList {
 
+    public static RecipeHandlerList NO_DATA = new RecipeHandlerList(IO.NONE);
+
     public static final Comparator<RecipeHandlerList> COMPARATOR = (h1, h2) -> {
         int cmp = Long.compare(h1.getPriority(), h2.getPriority());
         if (cmp != 0) return cmp;