Optimize Captured TileEntity Lookup

upstream was doing a containsKey/get pattern, and always doing it at that.
that scenario is only even valid if were in the middle of a block place.

Optimize to check if the captured list even has values in it, and also to
just do a get call since the value can never be null.

Spigot-Server-Patches/Optimize-Captured-TileEntity-Lookup.patch

@@ -0,0 +1,33 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Sat, 6 Apr 2019 10:16:48 -0400
+Subject: [PATCH] Optimize Captured TileEntity Lookup
+
+upstream was doing a containsKey/get pattern, and always doing it at that.
+that scenario is only even valid if were in the middle of a block place.
+
+Optimize to check if the captured list even has values in it, and also to
+just do a get call since the value can never be null.
+
+diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
+index 0e8025d311..b940f95bdb 100644
+--- a/src/main/java/net/minecraft/server/World.java
++++ b/src/main/java/net/minecraft/server/World.java
+@@ -0,0 +0,0 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
+             return null;
+         } else {
+             // CraftBukkit start
+-            if (capturedTileEntities.containsKey(blockposition)) {
+-                return capturedTileEntities.get(blockposition);
++            TileEntity tileentity = null; // Paper
++            if (!capturedTileEntities.isEmpty() && (tileentity = capturedTileEntities.get(blockposition)) != null) { // Paper
++                return tileentity; // Paper
+             }
+             // CraftBukkit end
+ 
+-            TileEntity tileentity = null;
++            //TileEntity tileentity = null; // Paper - move up
+ 
+             if (this.J) {
+                 tileentity = this.E(blockposition);
+--