don't check convert signs boolean every sign save

that lookup isn't "cheap", and synchronizes so cache it to a boolean instead

Spigot-Server-Patches/0421-Don-t-check-ConvertSigns-boolean-every-sign-save.patch

@@ -0,0 +1,32 @@
+From a32e8aa75982020a347efc307017e3f03b81c1c0 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Sat, 2 Mar 2019 11:11:29 -0500
+Subject: [PATCH] Don't check ConvertSigns boolean every sign save
+
+property lookups arent super cheap. they synchronize, validate
+and check security managers.
+
+diff --git a/src/main/java/net/minecraft/server/TileEntitySign.java b/src/main/java/net/minecraft/server/TileEntitySign.java
+index fdb771317a..d0a91f6755 100644
+--- a/src/main/java/net/minecraft/server/TileEntitySign.java
++++ b/src/main/java/net/minecraft/server/TileEntitySign.java
+@@ -15,6 +15,7 @@ public class TileEntitySign extends TileEntity implements ICommandListener {
+     private static final boolean keepInvalidUnicode = Boolean.getBoolean("Paper.keepInvalidUnicode"); // Allow people to keep their bad unicode if they really want it
+     private boolean privateUnicodeRemoved = false;
+     public java.util.UUID signEditor;
++    private static final boolean CONVERT_LEGACY_SIGNS = Boolean.getBoolean("convertLegacySigns");
+     // Paper end
+ 
+     public TileEntitySign() {
+@@ -31,7 +32,7 @@ public class TileEntitySign extends TileEntity implements ICommandListener {
+         }
+ 
+         // CraftBukkit start
+-        if (Boolean.getBoolean("convertLegacySigns")) {
++        if (CONVERT_LEGACY_SIGNS) { // Paper
+             nbttagcompound.setBoolean("Bukkit.isConverted", true);
+         }
+         // CraftBukkit end
+-- 
+2.20.1
+