Add Neo CustomLoaderBuilder for class model loader, for blocks.

Author: covers1624

src/main/java/codechicken/lib/datagen/ClassModelLoaderBuilder.java

@@ -0,0 +1,47 @@
+package codechicken.lib.datagen;
+
+import com.google.gson.JsonObject;
+import net.minecraft.client.resources.model.BakedModel;
+import net.minecraft.resources.ResourceLocation;
+import net.neoforged.neoforge.client.model.generators.CustomLoaderBuilder;
+import net.neoforged.neoforge.client.model.generators.ModelBuilder;
+import net.neoforged.neoforge.common.data.ExistingFileHelper;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Modifier;
+
+import static codechicken.lib.CodeChickenLib.MOD_ID;
+import static java.util.Objects.requireNonNull;
+
+/**
+ * Created by covers1624 on 1/21/25.
+ */
+public class ClassModelLoaderBuilder<T extends ModelBuilder<T>> extends CustomLoaderBuilder<T> {
+
+    private @Nullable Class<? extends BakedModel> clazz;
+
+    public ClassModelLoaderBuilder(T parent, ExistingFileHelper existingFileHelper) {
+        super(ResourceLocation.fromNamespaceAndPath(MOD_ID, "class"), parent, existingFileHelper, false);
+    }
+
+    public ClassModelLoaderBuilder<T> clazz(Class<? extends BakedModel> clazz) {
+        try {
+            Constructor<?> ctor = clazz.getConstructor();
+            if (!Modifier.isPublic(ctor.getModifiers())) {
+                throw new IllegalArgumentException("Expected single no-args public constructor.");
+            }
+        } catch (NoSuchMethodException ex) {
+            throw new IllegalStateException("Expected single no-args public constructor.", ex);
+        }
+        this.clazz = clazz;
+        return this;
+    }
+
+    @Override
+    public JsonObject toJson(JsonObject json) {
+        super.toJson(json);
+        json.addProperty("class", requireNonNull(clazz).getName());
+        return json;
+    }
+}