From 2d54f61a4602a74fcef2baae8741a3cafe5a6fea Mon Sep 17 00:00:00 2001
From: Evan McClain <aeroevan@gmail.com>
Date: Thu, 3 Oct 2024 15:28:39 -0400
Subject: [PATCH] AVRO-4072: Add AvroOrder for ReflectData

---
 .../org/apache/avro/reflect/AvroOrder.java    | 34 +++++++++++++++++++
 .../org/apache/avro/reflect/ReflectData.java  |  6 +++-
 .../org/apache/avro/reflect/TestReflect.java  | 18 ++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 lang/java/avro/src/main/java/org/apache/avro/reflect/AvroOrder.java

diff --git a/lang/java/avro/src/main/java/org/apache/avro/reflect/AvroOrder.java b/lang/java/avro/src/main/java/org/apache/avro/reflect/AvroOrder.java
new file mode 100644
index 00000000000..da00e55b33e
--- /dev/null
+++ b/lang/java/avro/src/main/java/org/apache/avro/reflect/AvroOrder.java
@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.avro.reflect;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.apache.avro.Schema;
+
+/**
+ * Sets the field order for this java field.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.FIELD })
+public @interface AvroOrder {
+  Schema.Field.Order value();
+}
diff --git a/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java b/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java
index 4ead6b888f4..ef385c99d8a 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java
@@ -744,7 +744,11 @@ protected Schema createSchema(Type type, Map<String, Schema> names) {
               if (STRING_OUTER_PARENT_REFERENCE.equals(fieldName)) {
                 throw new AvroTypeException("Class " + fullName + " must be a static inner class");
               }
-              Schema.Field recordField = new Schema.Field(fieldName, fieldSchema, doc, defaultValue);
+
+              AvroOrder fieldOrder = field.getAnnotation(AvroOrder.class);
+              Schema.Field recordField = (null == fieldOrder)
+                  ? new Schema.Field(fieldName, fieldSchema, doc, defaultValue)
+                  : new Schema.Field(fieldName, fieldSchema, doc, defaultValue, fieldOrder.value());
 
               AvroMeta[] metadata = field.getAnnotationsByType(AvroMeta.class); // add metadata
               for (AvroMeta meta : metadata) {
diff --git a/lang/java/avro/src/test/java/org/apache/avro/reflect/TestReflect.java b/lang/java/avro/src/test/java/org/apache/avro/reflect/TestReflect.java
index e3065d59b87..d3506454c4f 100644
--- a/lang/java/avro/src/test/java/org/apache/avro/reflect/TestReflect.java
+++ b/lang/java/avro/src/test/java/org/apache/avro/reflect/TestReflect.java
@@ -1349,4 +1349,22 @@ public void testAvroDoc() {
             + "{\"name\":\"foo\",\"type\":\"int\",\"doc\":\"Some Documentation\"}" + "]}");
   }
 
+  private static class OrderTest {
+    @AvroOrder(Field.Order.IGNORE)
+    int foo;
+    @AvroOrder(Field.Order.DESCENDING)
+    String bar;
+    String fooBar;
+  }
+
+  @Test
+  public void testAvroOrder() {
+    Schema schema = ReflectData.get().getSchema(OrderTest.class);
+
+    assertEquals(schema.getField("foo").order(), Field.Order.IGNORE);
+    assertEquals(schema.getField("bar").order(), Field.Order.DESCENDING);
+    // NOTE: The default field order is ASCENDING
+    assertEquals(schema.getField("fooBar").order(), Field.Order.ASCENDING);
+  }
+
 }