Don't move existing players to world spawn

This can cause a nasty server lag the spawn chunks are not kept loaded
or they aren't finished loading yet, or if the world spawn radius is
larger than the keep loaded range.

By skipping this, we avoid potential for a large spike on server start.

Spigot-Server-Patches/0463-Don-t-move-existing-players-to-world-spawn.patch

@@ -0,0 +1,47 @@
+From 404a073a8857173b0ce83f1defeda6ec6fe3049c Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Thu, 9 Apr 2020 21:20:33 -0400
+Subject: [PATCH] Don't move existing players to world spawn
+
+This can cause a nasty server lag the spawn chunks are not kept loaded
+or they aren't finished loading yet, or if the world spawn radius is
+larger than the keep loaded range.
+
+By skipping this, we avoid potential for a large spike on server start.
+
+diff --git a/src/main/java/net/minecraft/server/EntityPlayer.java b/src/main/java/net/minecraft/server/EntityPlayer.java
+index f44825090f..fb38975830 100644
+--- a/src/main/java/net/minecraft/server/EntityPlayer.java
++++ b/src/main/java/net/minecraft/server/EntityPlayer.java
+@@ -118,7 +118,7 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
+         this.serverStatisticManager = minecraftserver.getPlayerList().getStatisticManager(this);
+         this.advancementDataPlayer = minecraftserver.getPlayerList().f(this);
+         this.H = 1.0F;
+-        this.a(worldserver);
++        //this.a(worldserver); // Paper - don't move to spawn on login, only first join
+ 
+         this.cachedSingleHashSet = new com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<>(this); // Paper
+ 
+@@ -166,6 +166,7 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
+     }
+     // CraftBukkit end
+ 
++    public void moveToSpawn(WorldServer worldserver) { a(worldserver); } // Paper - OBFHELPER
+     private void a(WorldServer worldserver) {
+         BlockPosition blockposition = worldserver.getSpawn();
+ 
+diff --git a/src/main/java/net/minecraft/server/PlayerList.java b/src/main/java/net/minecraft/server/PlayerList.java
+index f37be4b76b..6d6fbf2f50 100644
+--- a/src/main/java/net/minecraft/server/PlayerList.java
++++ b/src/main/java/net/minecraft/server/PlayerList.java
+@@ -108,6 +108,7 @@ public abstract class PlayerList {
+             NBTTagCompound bukkit = nbttagcompound.getCompound("bukkit");
+             s = bukkit.hasKeyOfType("lastKnownName", 8) ? bukkit.getString("lastKnownName") : s;
+         }
++        if (nbttagcompound == null) entityplayer.moveToSpawn(worldserver); // Paper - only move to spawn on first login, otherwise, stay where you are....
+         // CraftBukkit end
+ 
+         // Paper start - support PlayerInitialSpawnEvent
+-- 
+2.25.1
+