From 93d110715eed5843d746a1412dc9033216cf172f Mon Sep 17 00:00:00 2001
From: Michael Himing <mhiming@gmail.com>
Date: Mon, 9 Sep 2019 13:21:17 +1000
Subject: [PATCH] Fix nether portal creation


diff --git a/src/main/java/org/bukkit/craftbukkit/util/BlockStateListPopulator.java b/src/main/java/org/bukkit/craftbukkit/util/BlockStateListPopulator.java
index 60330f753..c22dbbfbe 100644
--- a/src/main/java/org/bukkit/craftbukkit/util/BlockStateListPopulator.java
+++ b/src/main/java/org/bukkit/craftbukkit/util/BlockStateListPopulator.java
@@ -38,6 +38,11 @@ public class BlockStateListPopulator extends DummyGeneratorAccess {
 
     @Override
     public boolean setTypeAndData(BlockPosition position, IBlockData data, int flag) {
+        // Paper start
+        // When a LinkedHashMap entry is overwritten, it keeps its old position. Removing the entry here before adding
+        // a new one ensures that the nether portal blocks are placed last and are not destroyed by physics.
+        list.remove(position);
+        // Paper end
         CraftBlockState state = CraftBlockState.getBlockState(world, position, flag);
         state.setData(data);
         list.put(position, state);
-- 
2.25.0