PaperMC/paper-server/nms-patches/net/minecraft/world/item/ItemDye.patch

--- a/net/minecraft/world/item/ItemDye.java
+++ b/net/minecraft/world/item/ItemDye.java
@@ -11,6 +11,8 @@
 import net.minecraft.world.entity.animal.EntitySheep;
 import net.minecraft.world.entity.player.EntityHuman;
 
+import org.bukkit.event.entity.SheepDyeWoolEvent; // CraftBukkit
+
 public class ItemDye extends Item {
 
     private static final Map<EnumColor, ItemDye> ITEM_BY_COLOR = Maps.newEnumMap(EnumColor.class);
@@ -30,7 +32,17 @@
             if (entitysheep.isAlive() && !entitysheep.isSheared() && entitysheep.getColor() != this.dyeColor) {
                 entitysheep.level.playSound(entityhuman, (Entity) entitysheep, SoundEffects.DYE_USE, SoundCategory.PLAYERS, 1.0F, 1.0F);
                 if (!entityhuman.level.isClientSide) {
-                    entitysheep.setColor(this.dyeColor);
+                    // CraftBukkit start
+                    byte bColor = (byte) this.dyeColor.getColorIndex();
+                    SheepDyeWoolEvent event = new SheepDyeWoolEvent((org.bukkit.entity.Sheep) entitysheep.getBukkitEntity(), org.bukkit.DyeColor.getByWoolData(bColor));
+                    entitysheep.level.getCraftServer().getPluginManager().callEvent(event);
+
+                    if (event.isCancelled()) {
+                        return EnumInteractionResult.PASS;
+                    }
+
+                    entitysheep.setColor(EnumColor.fromColorIndex((byte) event.getColor().getWoolData()));
+                    // CraftBukkit end
                     itemstack.subtract(1);
                 }