Fix unpredictability in MachineMultiblock.getMainBlock()

src/main/java/com/mraof/minestuck/block/machine/MachineMultiblock.java

@@ -14,7 +14,10 @@
 import net.neoforged.neoforge.registries.DeferredRegister;
 
 import javax.annotation.Nonnull;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
 import java.util.function.BiPredicate;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
@@ -27,7 +30,7 @@ public abstract class MachineMultiblock implements ItemLike    //An abstraction
 	public static final BiPredicate<BlockState, BlockState> ROTATION_PREDICATE = BASE_PREDICATE.and((state1, state2) -> state1.getValue(MachineBlock.FACING) == state2.getValue(MachineBlock.FACING));
 
 	private final DeferredRegister.Blocks register;
-	private final Set<Supplier<? extends Block>> registryEntries = new HashSet<>();
+	private final List<Supplier<? extends Block>> registryEntries = new ArrayList<>();
 	private final List<PlacementEntry> blockEntries = new ArrayList<>();
 
 	protected MachineMultiblock(DeferredRegister.Blocks register)
@@ -96,7 +99,7 @@ protected PlacementEntry addPlacement(BlockPos pos, Supplier<BlockState> stateSu
 
 	public Block getMainBlock()
 	{
-		return !registryEntries.isEmpty() ? registryEntries.iterator().next().get() : null;
+		return !registryEntries.isEmpty() ? registryEntries.get(0).get() : null;
 	}
 
 	public void forEachBlock(Consumer<Block> consumer)