Enforce deterministic field order in Schema generated from KafkaIO classes.

To prevent potential serialization issues, this change adds the `@SchemaFieldNumber` annotation to KafkaIO classes that use `DefaultSchema`. This guarantees a deterministic field order, which is not ensured when schemas are generated with `AutoValueSchema`, `JavaBeanSchema`, or `JavaFieldSchema`.

Author: baeminbo

sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/providers/ErrorHandling.java

@@ -22,11 +22,13 @@
 import javax.annotation.Nullable;
 import org.apache.beam.sdk.schemas.Schema;
 import org.apache.beam.sdk.schemas.annotations.SchemaFieldDescription;
+import org.apache.beam.sdk.schemas.annotations.SchemaFieldNumber;
 import org.apache.beam.sdk.values.Row;
 
 @AutoValue
 public abstract class ErrorHandling implements Serializable {
   @SchemaFieldDescription("The name of the output PCollection containing failed writes.")
+  @SchemaFieldNumber("0")
   public abstract String getOutput();
 
   public static Builder builder() {

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaIO.java

@@ -70,6 +70,7 @@
 import org.apache.beam.sdk.schemas.SchemaRegistry;
 import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
 import org.apache.beam.sdk.schemas.annotations.SchemaCreate;
+import org.apache.beam.sdk.schemas.annotations.SchemaFieldNumber;
 import org.apache.beam.sdk.schemas.transforms.Convert;
 import org.apache.beam.sdk.transforms.Create;
 import org.apache.beam.sdk.transforms.DoFn;
@@ -2202,8 +2203,10 @@ public void populateDisplayData(DisplayData.Builder builder) {
    * generating Rows.
    */
   static class KafkaHeader {
-
+    @SchemaFieldNumber("0")
     String key;
+
+    @SchemaFieldNumber("1")
     byte @Nullable [] value;
 
     @SchemaCreate
@@ -2222,15 +2225,32 @@ public KafkaHeader(String key, byte @Nullable [] value) {
    * Schema inference supports generics.
    */
   static class ByteArrayKafkaRecord {
-
+    @SchemaFieldNumber("0")
     String topic;
+
+    @SchemaFieldNumber("1")
     int partition;
+
+    @SchemaFieldNumber("2")
     long offset;
+
+    @SchemaFieldNumber("3")
     long timestamp;
+
+    @SchemaFieldNumber("4")
     byte @Nullable [] key;
+
+    @SchemaFieldNumber("5")
     byte @Nullable [] value;
-    @Nullable List<KafkaHeader> headers;
+
+    @SchemaFieldNumber("6")
+    @Nullable
+    List<KafkaHeader> headers;
+
+    @SchemaFieldNumber("7")
     int timestampTypeId;
+
+    @SchemaFieldNumber("8")
     String timestampTypeName;
 
     @SchemaCreate

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaReadSchemaTransformConfiguration.java

@@ -27,6 +27,7 @@
 import org.apache.beam.sdk.schemas.AutoValueSchema;
 import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
 import org.apache.beam.sdk.schemas.annotations.SchemaFieldDescription;
+import org.apache.beam.sdk.schemas.annotations.SchemaFieldNumber;
 import org.apache.beam.sdk.schemas.transforms.providers.ErrorHandling;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Sets;
 
@@ -98,16 +99,20 @@ public static Builder builder() {
           + " Kafka cluster. The client will make use of all servers irrespective of which servers are specified"
           + " here for bootstrapping—this list only impacts the initial hosts used to discover the full set"
           + " of servers. This list should be in the form `host1:port1,host2:port2,...`")
+  @SchemaFieldNumber("0")
   public abstract String getBootstrapServers();
 
+  @SchemaFieldNumber("1")
   @Nullable
   public abstract String getConfluentSchemaRegistryUrl();
 
   @SchemaFieldDescription(
       "The encoding format for the data stored in Kafka. Valid options are: " + VALID_FORMATS_STR)
+  @SchemaFieldNumber("2")
   @Nullable
   public abstract String getFormat();
 
+  @SchemaFieldNumber("3")
   @Nullable
   public abstract String getConfluentSchemaRegistrySubject();
 
@@ -118,18 +123,21 @@ public static Builder builder() {
           + "For JSON data, this is a schema defined with JSON-schema syntax (https://json-schema.org/). "
           + "If a URL to Confluent Schema Registry is provided, then this field is ignored, and the schema "
           + "is fetched from Confluent Schema Registry.")
+  @SchemaFieldNumber("4")
   @Nullable
   public abstract String getSchema();
 
   @SchemaFieldDescription(
       "The path to the Protocol Buffer File Descriptor Set file. This file is used for schema"
           + " definition and message serialization.")
+  @SchemaFieldNumber("5")
   @Nullable
   public abstract String getFileDescriptorPath();
 
   @SchemaFieldDescription(
       "The name of the Protocol Buffer message to be used for schema"
           + " extraction and data conversion.")
+  @SchemaFieldNumber("6")
   @Nullable
   public abstract String getMessageName();
 
@@ -138,6 +146,7 @@ public static Builder builder() {
           + " does not exist any more on the server. (1) earliest: automatically reset the offset to the earliest"
           + " offset. (2) latest: automatically reset the offset to the latest offset"
           + " (3) none: throw exception to the consumer if no previous offset is found for the consumer’s group")
+  @SchemaFieldNumber("7")
   @Nullable
   public abstract String getAutoOffsetResetConfig();
 
@@ -146,17 +155,21 @@ public static Builder builder() {
           + " Most of these configurations will not be needed, but if you need to customize your Kafka consumer,"
           + " you may use this. See a detailed list:"
           + " https://docs.confluent.io/platform/current/installation/configuration/consumer-configs.html")
+  @SchemaFieldNumber("8")
   @Nullable
   public abstract Map<String, String> getConsumerConfigUpdates();
 
   /** Sets the topic from which to read. */
+  @SchemaFieldNumber("9")
   public abstract String getTopic();
 
   @SchemaFieldDescription("Upper bound of how long to read from Kafka.")
+  @SchemaFieldNumber("10")
   @Nullable
   public abstract Integer getMaxReadTimeSeconds();
 
   @SchemaFieldDescription("This option specifies whether and where to output unwritable rows.")
+  @SchemaFieldNumber("11")
   @Nullable
   public abstract ErrorHandling getErrorHandling();
 

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaSourceDescriptor.java

@@ -26,6 +26,7 @@
 import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
 import org.apache.beam.sdk.schemas.annotations.SchemaCreate;
 import org.apache.beam.sdk.schemas.annotations.SchemaFieldName;
+import org.apache.beam.sdk.schemas.annotations.SchemaFieldNumber;
 import org.apache.beam.sdk.schemas.annotations.SchemaIgnore;
 import org.apache.kafka.common.TopicPartition;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -38,30 +39,37 @@
 @AutoValue
 public abstract class KafkaSourceDescriptor implements Serializable {
   @SchemaFieldName("topic")
+  @SchemaFieldNumber("0")
   @Pure
   abstract String getTopic();
 
   @SchemaFieldName("partition")
+  @SchemaFieldNumber("1")
   @Pure
   abstract Integer getPartition();
 
   @SchemaFieldName("start_read_offset")
+  @SchemaFieldNumber("2")
   @Pure
   abstract @Nullable Long getStartReadOffset();
 
   @SchemaFieldName("start_read_time")
+  @SchemaFieldNumber("3")
   @Pure
   abstract @Nullable Instant getStartReadTime();
 
   @SchemaFieldName("stop_read_offset")
+  @SchemaFieldNumber("4")
   @Pure
   abstract @Nullable Long getStopReadOffset();
 
   @SchemaFieldName("stop_read_time")
+  @SchemaFieldNumber("5")
   @Pure
   abstract @Nullable Instant getStopReadTime();
 
   @SchemaFieldName("bootstrap_servers")
+  @SchemaFieldNumber("6")
   @Pure
   abstract @Nullable List<String> getBootStrapServers();
 

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaWriteSchemaTransformProvider.java

@@ -44,6 +44,7 @@
 import org.apache.beam.sdk.schemas.SchemaRegistry;
 import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
 import org.apache.beam.sdk.schemas.annotations.SchemaFieldDescription;
+import org.apache.beam.sdk.schemas.annotations.SchemaFieldNumber;
 import org.apache.beam.sdk.schemas.transforms.SchemaTransform;
 import org.apache.beam.sdk.schemas.transforms.SchemaTransformProvider;
 import org.apache.beam.sdk.schemas.transforms.TypedSchemaTransformProvider;
@@ -339,41 +340,49 @@ public abstract static class KafkaWriteSchemaTransformConfiguration implements S
     @SchemaFieldDescription(
         "The encoding format for the data stored in Kafka. Valid options are: "
             + SUPPORTED_FORMATS_STR)
+    @SchemaFieldNumber("0")
     public abstract String getFormat();
 
+    @SchemaFieldNumber("1")
     public abstract String getTopic();
 
     @SchemaFieldDescription(
         "A list of host/port pairs to use for establishing the initial connection to the"
             + " Kafka cluster. The client will make use of all servers irrespective of which servers are specified"
             + " here for bootstrapping—this list only impacts the initial hosts used to discover the full set"
             + " of servers. | Format: host1:port1,host2:port2,...")
+    @SchemaFieldNumber("2")
     public abstract String getBootstrapServers();
 
     @SchemaFieldDescription(
         "A list of key-value pairs that act as configuration parameters for Kafka producers."
             + " Most of these configurations will not be needed, but if you need to customize your Kafka producer,"
             + " you may use this. See a detailed list:"
             + " https://docs.confluent.io/platform/current/installation/configuration/producer-configs.html")
+    @SchemaFieldNumber("3")
     @Nullable
     public abstract Map<String, String> getProducerConfigUpdates();
 
     @SchemaFieldDescription("This option specifies whether and where to output unwritable rows.")
+    @SchemaFieldNumber("4")
     @Nullable
     public abstract ErrorHandling getErrorHandling();
 
     @SchemaFieldDescription(
         "The path to the Protocol Buffer File Descriptor Set file. This file is used for schema"
             + " definition and message serialization.")
+    @SchemaFieldNumber("5")
     @Nullable
     public abstract String getFileDescriptorPath();
 
     @SchemaFieldDescription(
         "The name of the Protocol Buffer message to be used for schema"
             + " extraction and data conversion.")
+    @SchemaFieldNumber("6")
     @Nullable
     public abstract String getMessageName();
 
+    @SchemaFieldNumber("7")
     @Nullable
     public abstract String getSchema();
 

sdks/java/io/kafka/src/test/java/org/apache/beam/sdk/io/kafka/KafkaIOTest.java

@@ -91,6 +91,9 @@
 import org.apache.beam.sdk.metrics.SourceMetrics;
 import org.apache.beam.sdk.options.PipelineOptionsFactory;
 import org.apache.beam.sdk.options.StreamingOptions;
+import org.apache.beam.sdk.schemas.NoSuchSchemaException;
+import org.apache.beam.sdk.schemas.Schema;
+import org.apache.beam.sdk.schemas.SchemaRegistry;
 import org.apache.beam.sdk.testing.ExpectedLogs;
 import org.apache.beam.sdk.testing.PAssert;
 import org.apache.beam.sdk.testing.TestPipeline;
@@ -2450,6 +2453,62 @@ public void testWithValidConsumerPollingTimeout() {
     assertEquals(15, reader.getConsumerPollingTimeout());
   }
 
+  // This test verifies that the schema for KafkaIO.ByteArrayKafkaRecord is correctly generated.
+  // This schema is used when Kafka records are serialized/deserialized with SchemaCoder.
+  @Test
+  public void testByteArrayKafkaRecordSchema() throws NoSuchSchemaException {
+    Schema schema = SchemaRegistry.createDefault().getSchema(KafkaIO.ByteArrayKafkaRecord.class);
+
+    assertEquals(9, schema.getFieldCount());
+    assertEquals(Schema.Field.of("topic", Schema.FieldType.STRING), schema.getField(0));
+    assertEquals(Schema.Field.of("partition", Schema.FieldType.INT32), schema.getField(1));
+    assertEquals(Schema.Field.of("offset", Schema.FieldType.INT64), schema.getField(2));
+    assertEquals(Schema.Field.of("timestamp", Schema.FieldType.INT64), schema.getField(3));
+    assertEquals(Schema.Field.nullable("key", Schema.FieldType.BYTES), schema.getField(4));
+    assertEquals(Schema.Field.nullable("value", Schema.FieldType.BYTES), schema.getField(5));
+    assertEquals(
+        Schema.Field.nullable(
+            "headers",
+            Schema.FieldType.array(
+                Schema.FieldType.row(
+                    Schema.of(
+                        Schema.Field.of("key", Schema.FieldType.STRING),
+                        Schema.Field.nullable("value", Schema.FieldType.BYTES))))),
+        schema.getField(6));
+    assertEquals(Schema.Field.of("timestampTypeId", Schema.FieldType.INT32), schema.getField(7));
+    assertEquals(Schema.Field.of("timestampTypeName", Schema.FieldType.STRING), schema.getField(8));
+  }
+
+  // This test verifies that the schema for KafkaSourceDescriptor is correctly generated.
+  @Test
+  public void testKafkaSourceDescriptorSchema() throws NoSuchSchemaException {
+    Schema schema = SchemaRegistry.createDefault().getSchema(KafkaSourceDescriptor.class);
+
+    assertEquals(7, schema.getFieldCount());
+    assertEquals(Schema.Field.of("topic", Schema.FieldType.STRING), schema.getField(0));
+    assertEquals(Schema.Field.of("partition", Schema.FieldType.INT32), schema.getField(1));
+    assertEquals(
+        Schema.Field.nullable("start_read_offset", Schema.FieldType.INT64), schema.getField(2));
+    assertEquals(
+        Schema.Field.nullable("start_read_time", Schema.FieldType.DATETIME), schema.getField(3));
+    assertEquals(
+        Schema.Field.nullable("stop_read_offset", Schema.FieldType.INT64), schema.getField(4));
+    assertEquals(
+        Schema.Field.nullable("stop_read_time", Schema.FieldType.DATETIME), schema.getField(5));
+    assertEquals(
+        Schema.Field.nullable("bootstrap_servers", Schema.FieldType.array(Schema.FieldType.STRING)),
+        schema.getField(6));
+  }
+
+  @Test
+  public void testKafkaHeaderSchema() throws NoSuchSchemaException {
+    Schema schema = SchemaRegistry.createDefault().getSchema(KafkaIO.KafkaHeader.class);
+
+    assertEquals(2, schema.getFieldCount());
+    assertEquals(Schema.Field.of("key", Schema.FieldType.STRING), schema.getField(0));
+    assertEquals(Schema.Field.nullable("value", Schema.FieldType.BYTES), schema.getField(1));
+  }
+
   private static void verifyProducerRecords(
       MockProducer<Integer, Long> mockProducer,
       String topic,