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

--- a/net/minecraft/world/item/ItemFishingRod.java
+++ b/net/minecraft/world/item/ItemFishingRod.java
@@ -13,6 +13,11 @@
 import net.minecraft.world.level.World;
 import net.minecraft.world.level.gameevent.GameEvent;
 
+// CraftBukkit start
+import org.bukkit.event.player.PlayerFishEvent;
+import org.bukkit.craftbukkit.CraftEquipmentSlot;
+// CraftBukkit end
+
 public class ItemFishingRod extends Item {
 
     public ItemFishingRod(Item.Info item_info) {
@@ -33,13 +38,24 @@
             world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.FISHING_BOBBER_RETRIEVE, SoundCategory.NEUTRAL, 1.0F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
             entityhuman.gameEvent(GameEvent.ITEM_INTERACT_FINISH);
         } else {
-            world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.FISHING_BOBBER_THROW, SoundCategory.NEUTRAL, 0.5F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
+            // world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.FISHING_BOBBER_THROW, SoundCategory.NEUTRAL, 0.5F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
             if (world instanceof WorldServer) {
                 WorldServer worldserver = (WorldServer) world;
                 int j = (int) (EnchantmentManager.getFishingTimeReduction(worldserver, itemstack, entityhuman) * 20.0F);
                 int k = EnchantmentManager.getFishingLuckBonus(worldserver, itemstack, entityhuman);
 
-                world.addFreshEntity(new EntityFishingHook(entityhuman, world, k, j));
+                // CraftBukkit start
+                EntityFishingHook entityfishinghook = new EntityFishingHook(entityhuman, world, k, j);
+                PlayerFishEvent playerFishEvent = new PlayerFishEvent((org.bukkit.entity.Player) entityhuman.getBukkitEntity(), null, (org.bukkit.entity.FishHook) entityfishinghook.getBukkitEntity(), CraftEquipmentSlot.getHand(enumhand), PlayerFishEvent.State.FISHING);
+                world.getCraftServer().getPluginManager().callEvent(playerFishEvent);
+
+                if (playerFishEvent.isCancelled()) {
+                    entityhuman.fishing = null;
+                    return InteractionResultWrapper.pass(itemstack);
+                }
+                world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.FISHING_BOBBER_THROW, SoundCategory.NEUTRAL, 0.5F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
+                world.addFreshEntity(entityfishinghook);
+                // CraftBukkit end
             }
 
             entityhuman.awardStat(StatisticList.ITEM_USED.get(this));