papermc/patches/server/0495-Fix-curing-zombie-villager-discount-exploit.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: BillyGalbreath <blake.galbreath@gmail.com>
Date: Tue, 8 Dec 2020 20:14:20 -0600
Subject: [PATCH] Fix curing zombie villager discount exploit

This fixes the exploit used to gain absurd trading discounts with infecting
and curing a villager on repeat by simply resetting the relevant part of
the reputation when it is cured.

diff --git a/src/main/java/net/minecraft/world/entity/npc/Villager.java b/src/main/java/net/minecraft/world/entity/npc/Villager.java
index 24434b66d158b10d21579b2db6efb0bdcc788a5c..0c78c1ccb1443dca7efc5a429b6020373fc7331e 100644
--- a/src/main/java/net/minecraft/world/entity/npc/Villager.java
+++ b/src/main/java/net/minecraft/world/entity/npc/Villager.java
@@ -1000,6 +1000,15 @@ public class Villager extends AbstractVillager implements ReputationEventHandler
     @Override
     public void onReputationEventFrom(ReputationEventType interaction, Entity entity) {
         if (interaction == ReputationEventType.ZOMBIE_VILLAGER_CURED) {
+            // Paper start - fix MC-181190
+            if (level.paperConfig().fixes.fixCuringZombieVillagerDiscountExploit) {
+                final GossipContainer.EntityGossips playerReputation = this.getGossips().gossips.get(entity.getUUID());
+                if (playerReputation != null) {
+                    playerReputation.remove(GossipType.MAJOR_POSITIVE);
+                    playerReputation.remove(GossipType.MINOR_POSITIVE);
+                }
+            }
+            // Paper end
             this.gossips.add(entity.getUUID(), GossipType.MAJOR_POSITIVE, 20);
             this.gossips.add(entity.getUUID(), GossipType.MINOR_POSITIVE, 25);
         } else if (interaction == ReputationEventType.TRADE) {