don't go below 0 for pickupDelay, breaks picking up items

vanilla checks for == 0

Fixes #1911

Spigot-Server-Patches/0180-PlayerPickupItemEvent-setFlyAtPlayer.patch

@@ -1,11 +1,11 @@
-From d2dc3091b8657b318b2813a1e3ab7a1eed394ae8 Mon Sep 17 00:00:00 2001
+From 1afd93a126d91c9ed1d852bc9c065c6dbdd29ec0 Mon Sep 17 00:00:00 2001
 From: BillyGalbreath <Blake.Galbreath@GMail.com>
 Date: Sun, 7 May 2017 06:26:09 -0500
 Subject: [PATCH] PlayerPickupItemEvent#setFlyAtPlayer
 
 
 diff --git a/src/main/java/net/minecraft/server/EntityItem.java b/src/main/java/net/minecraft/server/EntityItem.java
-index 39a804b7c..643793d55 100644
+index 39a804b7c..921a56c31 100644
 --- a/src/main/java/net/minecraft/server/EntityItem.java
 +++ b/src/main/java/net/minecraft/server/EntityItem.java
 @@ -308,6 +308,7 @@ public class EntityItem extends Entity {
@@ -30,10 +30,11 @@ index 39a804b7c..643793d55 100644
                      return;
                  }
  
-@@ -336,6 +343,11 @@ public class EntityItem extends Entity {
+@@ -335,7 +342,11 @@ public class EntityItem extends Entity {
+             // CraftBukkit end
  
              if (this.pickupDelay == 0 && (this.g == null || 6000 - this.age <= 200 || this.g.equals(entityhuman.getUniqueID())) && entityhuman.inventory.pickup(itemstack)) {
-                 entityhuman.receive(this, i);
+-                entityhuman.receive(this, i);
 +                // Paper Start
 +                if (flyAtPlayer) {
 +                    entityhuman.receive(this, i);

Spigot-Server-Patches/0378-Implement-getters-and-setters-for-EntityItem-owner-a.patch

@@ -1,4 +1,4 @@
-From bacfdeb718a1a43b35ea4cefdd5c1ca4bd00b434 Mon Sep 17 00:00:00 2001
+From 3b7348ab1fc8bd6b8918e0b6a4626ef178eb22aa Mon Sep 17 00:00:00 2001
 From: BillyGalbreath <Blake.Galbreath@GMail.com>
 Date: Sat, 6 Oct 2018 20:54:23 -0500
 Subject: [PATCH] Implement getters and setters for EntityItem owner and
@@ -6,10 +6,10 @@ Subject: [PATCH] Implement getters and setters for EntityItem owner and
 
 
 diff --git a/src/main/java/net/minecraft/server/EntityItem.java b/src/main/java/net/minecraft/server/EntityItem.java
-index 6752d0b8c..03fee65e4 100644
+index c9473087a..e723bd339 100644
 --- a/src/main/java/net/minecraft/server/EntityItem.java
 +++ b/src/main/java/net/minecraft/server/EntityItem.java
-@@ -411,20 +411,22 @@ public class EntityItem extends Entity {
+@@ -410,20 +410,22 @@ public class EntityItem extends Entity {
          this.getDataWatcher().markDirty(EntityItem.b); // CraftBukkit - SPIGOT-4591, must mark dirty
      }
  

Spigot-Server-Patches/0428-don-t-go-below-0-for-pickupDelay-breaks-picking-up-i.patch

@@ -0,0 +1,22 @@
+From 7b2b7b222801b793995cbc5b917933a50a47c772 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Sun, 24 Mar 2019 18:09:20 -0400
+Subject: [PATCH] don't go below 0 for pickupDelay, breaks picking up items
+
+vanilla checks for == 0
+
+diff --git a/src/main/java/net/minecraft/server/EntityItem.java b/src/main/java/net/minecraft/server/EntityItem.java
+index e723bd339..cf00d0c88 100644
+--- a/src/main/java/net/minecraft/server/EntityItem.java
++++ b/src/main/java/net/minecraft/server/EntityItem.java
+@@ -58,6 +58,7 @@ public class EntityItem extends Entity {
+             // CraftBukkit start - Use wall time for pickup and despawn timers
+             int elapsedTicks = MinecraftServer.currentTick - this.lastTick;
+             if (this.pickupDelay != 32767) this.pickupDelay -= elapsedTicks;
++            this.pickupDelay = Math.max(0, this.pickupDelay); // Paper - don't go below 0
+             if (this.age != -32768) this.age += elapsedTicks;
+             this.lastTick = MinecraftServer.currentTick;
+             // CraftBukkit end
+-- 
+2.21.0
+