Add demo thunder enchantment

src/main/generated/.cache/6f5192c797375035190f7e885b8d5d4aa840c2f5

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+// 1.21.1	2024-09-29T04:05:48.3198307	Custom Enchants/Enchantment Generator
+4e507987cd1905de26693915dff86bcadec7e9a0 data\customenchants\enchantment\thundering.json

src/main/generated/data/customenchants/enchantment/thundering.json

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+{
+  "anvil_cost": 7,
+  "description": {
+    "translate": "enchantment.customenchants.thundering"
+  },
+  "effects": {
+    "minecraft:post_attack": [
+      {
+        "affected": "victim",
+        "effect": {
+          "type": "customenchants:lightning",
+          "amount": {
+            "type": "minecraft:linear",
+            "base": 0.5,
+            "per_level_above_first": 0.15
+          }
+        },
+        "enchanted": "attacker"
+      }
+    ]
+  },
+  "max_cost": {
+    "base": 1,
+    "per_level_above_first": 15
+  },
+  "max_level": 5,
+  "min_cost": {
+    "base": 1,
+    "per_level_above_first": 10
+  },
+  "slots": [
+    "hand"
+  ],
+  "supported_items": "#minecraft:enchantable/sword",
+  "weight": 15
+}

src/main/java/com/itzilly/enchantments/effects/LightningEnchantmentEffect.java

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+package com.itzilly.enchantments.effects;
+
+import com.mojang.serialization.MapCodec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import net.minecraft.enchantment.EnchantmentEffectContext;
+import net.minecraft.enchantment.EnchantmentLevelBasedValue;
+import net.minecraft.enchantment.effect.EnchantmentEntityEffect;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.SpawnReason;
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.Vec3d;
+
+public record LightningEnchantmentEffect(EnchantmentLevelBasedValue amount) implements EnchantmentEntityEffect {
+    public static final MapCodec<LightningEnchantmentEffect> CODEC = RecordCodecBuilder.mapCodec(
+            instance -> instance.group(
+                    EnchantmentLevelBasedValue.CODEC.fieldOf("amount").forGetter(LightningEnchantmentEffect::amount)
+            ).apply(instance, LightningEnchantmentEffect::new));
+
+    @Override
+    public void apply(ServerWorld world, int level, EnchantmentEffectContext context, Entity target, Vec3d pos) {
+        if(target instanceof LivingEntity living) {
+            float numberOfStrikes = this.amount.getValue(level);
+
+            BlockPos targetPosition = living.getBlockPos();
+            for (int i = 0; i < numberOfStrikes; i++) {
+                EntityType.LIGHTNING_BOLT.spawn(world, targetPosition, SpawnReason.TRIGGERED);
+            }
+        }
+    }
+
+    @Override
+    public MapCodec<? extends EnchantmentEntityEffect> getCodec() {
+        return CODEC;
+    }
+}