Add mixin support and example mixin

src/main/java/com/bipolarexpedition/java/contraptions_are_safe/mixin/MobTargetingMixin.java

@@ -0,0 +1,33 @@
+package com.bipolarexpedition.java.contraptions_are_safe.mixin;
+
+import com.bipolarexpedition.java.contraptions_are_safe.ContraptionsAreSafe;
+import com.simibubi.create.content.contraptions.AbstractContraptionEntity;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.Mob;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+@Mixin(Mob.class)
+public class MobTargetingMixin {
+
+    @Inject(method = "canAttack(Lnet/minecraft/world/entity/LivingEntity;)Z", at = @At("HEAD"), cancellable = true)
+    private void preventContraptionTargeting(LivingEntity target, CallbackInfoReturnable<Boolean> cir) {
+        if (target != null && isOnContraption(target)) {
+            cir.setReturnValue(false);
+        }
+    }
+
+    private boolean isOnContraption(Entity entity) {
+        Entity vehicle = entity.getVehicle();
+        while (vehicle != null) {
+            if (vehicle instanceof AbstractContraptionEntity) {
+                return true;
+            }
+            vehicle = vehicle.getVehicle();
+        }
+        return false;
+    }
+}

src/main/resources/META-INF/mods.toml

@@ -41,6 +41,8 @@ authors="${mod_authors}" #optional
 # IMPORTANT NOTE: this is NOT an instruction as to which environments (CLIENT or DEDICATED SERVER) your mod loads on. Your mod should load (and maybe do nothing!) whereever it finds itself.
 #displayTest="MATCH_VERSION" # if nothing is specified, MATCH_VERSION is the default when clientSideOnly=false, otherwise IGNORE_ALL_VERSION when clientSideOnly=true (#optional)
 
+mixinConfig = "contraptionsaresafe.mixins.json"
+
 # Access Transformers
 # Optional, if not specified Forge will attempt to find the default META-INF/accesstransformer.cfg and silently continue if not found. May default to an empty list in a future MC.
 # If you specify AT path strings in this list, Forge will attempt to load each of them and throw errors for any that aren't found.

src/main/resources/contraptionsaresafe.mixins.json

@@ -0,0 +1,12 @@
+{
+  "required": true,
+  "minVersion": "0.8",
+  "package": "com.bipolarexpedition.java.contraptions_are_safe.mixin",
+  "compatibilityLevel": "JAVA_17",
+  "refmap": "contraptionsaresafe.refmap.json",
+  "mixins": [
+    "MobTargetingMixin"
+  ],
+  "client": [],
+  "server": []
+}