Fix deserializer reading from the wrong field on AddEntryLootModifier

See SlimeKnights/TinkersConstruct#5268

Was fixed on 1.19 as the codec migration ensured matching name on both
For 1.18, fixed by supporting both names for now, prioritize the new name but allow the old name if set. Datagen now uses the new name.

src/main/java/slimeknights/mantle/loot/AddEntryLootModifier.java

@@ -4,26 +4,23 @@
 import com.google.gson.JsonObject;
 import lombok.AccessLevel;
 import lombok.RequiredArgsConstructor;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.util.GsonHelper;
 import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.storage.loot.Deserializers;
 import net.minecraft.world.level.storage.loot.LootContext;
 import net.minecraft.world.level.storage.loot.entries.LootPoolEntryContainer;
-import net.minecraft.world.level.storage.loot.Deserializers;
-import net.minecraft.world.level.storage.loot.predicates.LootItemCondition;
 import net.minecraft.world.level.storage.loot.functions.LootItemFunction;
 import net.minecraft.world.level.storage.loot.functions.LootItemFunctions;
-import net.minecraft.util.GsonHelper;
-import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.storage.loot.predicates.LootItemCondition;
 import net.minecraftforge.common.data.GlobalLootModifierProvider;
 import net.minecraftforge.common.loot.GlobalLootModifierSerializer;
 import net.minecraftforge.common.loot.LootModifier;
-import slimeknights.mantle.Mantle;
 import slimeknights.mantle.loot.builder.AbstractLootModifierBuilder;
-import slimeknights.mantle.loot.condition.EmptyModifierLootCondition;
 import slimeknights.mantle.loot.condition.ILootModifierCondition;
 
 import javax.annotation.Nonnull;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
@@ -82,6 +79,8 @@ public AddEntryLootModifier read(ResourceLocation location, JsonObject object, L
       // loot modifier conditions
       ILootModifierCondition[] modifierConditions;
       if (object.has("post_conditions")) {
+        modifierConditions = GSON.fromJson(GsonHelper.getAsJsonArray(object, "post_conditions"), ILootModifierCondition[].class);
+      } else if (object.has("modifier_conditions")) {
         modifierConditions = GSON.fromJson(GsonHelper.getAsJsonArray(object, "modifier_conditions"), ILootModifierCondition[].class);
       } else {
         modifierConditions = new ILootModifierCondition[0];
@@ -101,7 +100,7 @@ public AddEntryLootModifier read(ResourceLocation location, JsonObject object, L
 		public JsonObject write(AddEntryLootModifier instance) {
 			JsonObject object = makeConditions(instance.conditions);
       if (instance.modifierConditions.length > 0) {
-        object.add("modifier_conditions", GSON.toJsonTree(instance.modifierConditions, ILootModifierCondition[].class));
+        object.add("post_conditions", GSON.toJsonTree(instance.modifierConditions, ILootModifierCondition[].class));
       }
 			object.add("entry", GSON.toJsonTree(instance.entry, LootPoolEntryContainer.class));
       if (instance.functions.length > 0) {