Let ICleanroomProviders have priorities and only set the cleanroom provider in RecipeMapMultiblockControllers if the priority is higher than the existing one.

Author: Zorbatron

src/main/java/gregtech/api/metatileentity/multiblock/DummyCleanroom.java

@@ -64,4 +64,11 @@ public void setCleanAmount(int amount) {}
 
     @Override
     public void adjustCleanAmount(int amount) {}
+
+    // Have a higher priority than the cleanroom multiblock (which doesn't override getPriority so it'll return 0)
+    // doesn't replace the set cleanroom in multiblocks.
+    @Override
+    public int getPriority() {
+        return 1;
+    }
 }

src/main/java/gregtech/api/metatileentity/multiblock/ICleanroomProvider.java

@@ -49,4 +49,13 @@ public interface ICleanroomProvider {
      * @return the tier {@link gregtech.api.GTValues#V} of energy the cleanroom uses at minimum
      */
     int getEnergyTier();
+
+    /**
+     * Get the priority of this cleanroom provider to determine which should be used.
+     * 
+     * @return the priority this cleanroom provider should have over other cleanrooms.
+     */
+    default int getPriority() {
+        return 0;
+    }
 }

src/main/java/gregtech/api/metatileentity/multiblock/RecipeMapMultiblockController.java

@@ -321,6 +321,8 @@ public ICleanroomProvider getCleanroom() {
 
     @Override
     public void setCleanroom(ICleanroomProvider provider) {
-        this.cleanroom = provider;
+        if (cleanroom == null || provider.getPriority() > cleanroom.getPriority()) {
+            this.cleanroom = provider;
+        }
     }
 }

src/main/java/gregtech/common/metatileentities/multi/multiblockpart/MetaTileEntityCleaningMaintenanceHatch.java

@@ -52,9 +52,9 @@ public MetaTileEntity createMetaTileEntity(IGregTechTileEntity tileEntity) {
     @Override
     public void addToMultiBlock(MultiblockControllerBase controllerBase) {
         super.addToMultiBlock(controllerBase);
-        if (controllerBase instanceof ICleanroomReceiver &&
-                ((ICleanroomReceiver) controllerBase).getCleanroom() == null) {
-            ((ICleanroomReceiver) controllerBase).setCleanroom(DUMMY_CLEANROOM);
+        if (controllerBase instanceof ICleanroomReceiver cleanroomReceiver &&
+                cleanroomReceiver.getCleanroom() == null) {
+            cleanroomReceiver.setCleanroom(DUMMY_CLEANROOM);
         }
     }