fix MC-299115 (closes #463) (#464)

Author: isXander

PATCHED.md

@@ -114,6 +114,8 @@
 | Basic    | [MC-271899](https://bugs.mojang.com/browse/MC-271899) | StructureTemplate Palette's caches are not thread safe                                                                                         |
 | Basic    | [MC-272431](https://bugs.mojang.com/browse/MC-272431) | Ender Dragon incorrect vertical velocity causes erratic behavior                                                                               |
 | Basic    | [MC-298066](https://bugs.mojang.com/browse/MC-298066) | Directly entering a bed from a mount places the player in the wrong place                                                                      |
+| Basic    | [MC-299115](https://bugs.mojang.com/browse/MC-299115) | Arrow losing owner tag when deflected whilst owner being offline                                                                               |
+|
 
 ## Previously patched
 Bugs that this mod has patched but has been superseded by a vanilla update.

src/main/java/dev/isxander/debugify/mixins/basic/mc299115/ProjectileMixin.java

@@ -0,0 +1,33 @@
+package dev.isxander.debugify.mixins.basic.mc299115;
+
+import com.llamalad7.mixinextras.injector.v2.WrapWithCondition;
+import dev.isxander.debugify.fixes.BugFix;
+import dev.isxander.debugify.fixes.FixCategory;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EntityReference;
+import net.minecraft.world.entity.projectile.Projectile;
+import org.jetbrains.annotations.Nullable;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+
+@BugFix(id = "MC-299115", category = FixCategory.BASIC, env = BugFix.Env.SERVER, description = "Arrow loses owner tag when deflected whilst owner is offline.")
+@Mixin(Projectile.class)
+public class ProjectileMixin {
+    @Shadow
+    @Nullable
+    protected EntityReference<Entity> owner;
+
+    /**
+     * This deflect method takes the `Entity` owner, not an `EntityReference<Entity>`.
+     * This means during deflection, the owner is resolved from its reference.
+     * Because the owner is no longer online, it is nullified.
+     */
+    @WrapWithCondition(method = "deflect", at = @At(value = "INVOKE", target = "Lnet/minecraft/world/entity/projectile/Projectile;setOwner(Lnet/minecraft/world/entity/Entity;)V"))
+    private boolean preventNullifyingOwner(Projectile instance, Entity owner) {
+        // only allow setting the owner if:
+        // 1. the new owner is not null
+        // 2. the current owner reference is null (which means it never had a reference to any owner)
+        return this.owner == null || owner != null;
+    }
+}

src/main/resources/debugify.mixins.json

@@ -23,8 +23,8 @@
     "basic.mc132878.ArmorStandMixin",
     "basic.mc134110.ChestBlockMixin",
     "basic.mc136249.LivingEntityMixin",
-    "basic.mc147659.CatSpawnerMixin",
     "basic.mc139041.FishingRodItemMixin",
+    "basic.mc147659.CatSpawnerMixin",
     "basic.mc147784.FletchingTableBlockMixin",
     "basic.mc155509.PufferfishMixin",
     "basic.mc159283.DensityFunctionsMixin",
@@ -44,12 +44,12 @@
     "basic.mc206922.EntityMixin",
     "basic.mc206922.ItemEntityMixin",
     "basic.mc215530.ServerPlayerMixin",
-    "basic.mc221257.ShulkerBulletMixin",
     "basic.mc219981.ZombieMixin",
+    "basic.mc221257.ShulkerBulletMixin",
     "basic.mc223153.BlocksMixin",
     "basic.mc224729.ChunkMapMixin",
-    "basic.mc227008.EnderManMixin",
     "basic.mc226961.ExperienceOrbMixin",
+    "basic.mc227008.EnderManMixin",
     "basic.mc227337.ShulkerBulletMixin",
     "basic.mc231743.FlowerPotBlockMixin",
     "basic.mc232869.StriderMixin",
@@ -59,6 +59,7 @@
     "basic.mc271899.StructureTemplateMixin",
     "basic.mc272431.EnderDragonMixin",
     "basic.mc298066.LivingEntityMixin",
+    "basic.mc299115.ProjectileMixin",
     "basic.mc30391.LivingEntityMixin",
     "basic.mc69216.ServerPlayerMixin",
     "basic.mc7569.RconConsoleSourceMixin",