add test code.

pulsar-broker/src/test/java/org/apache/pulsar/client/api/DeadLetterTopicTest.java

@@ -1055,8 +1055,7 @@ public void testDeadLetterTopicWithInitialSubscription() throws Exception {
 
     @Test()
     public void testDeadLetterTopicWithProducerBuilder() throws Exception {
-        final String suffix = "-with-producer-builder";
-        final String topic = "persistent://my-property/my-ns/dead-letter-topic" + suffix;
+        final String topic = "persistent://my-property/my-ns/dead-letter-topic-with-producer-builder";
         final int maxRedeliveryCount = 2;
         final int sendMessages = 100;
 

pulsar-broker/src/test/java/org/apache/pulsar/client/api/RetryTopicTest.java

@@ -32,6 +32,8 @@
 import java.util.UUID;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+
 import lombok.Cleanup;
 import lombok.Data;
 import org.apache.avro.AvroRuntimeException;
@@ -136,6 +138,85 @@ public void testRetryTopic() throws Exception {
         checkConsumer.close();
     }
 
+    @Test
+    public void testRetryTopicWithProducerBuilder() throws Exception {
+        final String topic = "persistent://my-property/my-ns/retry-topic-with-producer-builder";
+        final int maxRedeliveryCount = 2;
+        final int sendMessages = 100;
+
+        // enable batch
+        Function<String, ProducerBuilder<byte[]>> producerBuilderFunction = (topicName) -> {
+            ProducerBuilder<byte[]> producerBuilder = pulsarClient.newProducer(Schema.BYTES);
+            producerBuilder.topic(topicName).enableBatching(true);
+            return producerBuilder;
+        };
+        String subscriptionName = "my-subscription";
+        String subscriptionNameDLQ = "my-subscription-DLQ";
+        Consumer<byte[]> consumer = pulsarClient.newConsumer(Schema.BYTES)
+                .topic(topic)
+                .subscriptionName(subscriptionName)
+                .subscriptionType(SubscriptionType.Shared)
+                .enableRetry(true)
+                .deadLetterPolicy(DeadLetterPolicy.builder()
+                        .maxRedeliverCount(maxRedeliveryCount)
+                        .retryLetterProducerBuilder(producerBuilderFunction)
+                        .build())
+                .receiverQueueSize(100)
+                .subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
+                .subscribe();
+
+        @Cleanup
+        PulsarClient newPulsarClient = newPulsarClient(lookupUrl.toString(), 0);// Creates new client connection
+        Consumer<byte[]> deadLetterConsumer = newPulsarClient.newConsumer(Schema.BYTES)
+                .topic(topic + "-" + subscriptionName + "-DLQ")
+                .subscriptionName(subscriptionNameDLQ)
+                .subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
+                .subscribe();
+
+        Producer<byte[]> producer = pulsarClient.newProducer(Schema.BYTES)
+                .topic(topic)
+                .create();
+
+        for (int i = 0; i < sendMessages; i++) {
+            producer.send(String.format("Hello Pulsar [%d]", i).getBytes());
+        }
+        producer.close();
+
+        int totalReceived = 0;
+        do {
+            Message<byte[]> message = consumer.receive();
+            log.info("consumer received message : {} {}", message.getMessageId(), new String(message.getData()));
+            consumer.reconsumeLater(message, 1, TimeUnit.SECONDS);
+            totalReceived++;
+        } while (totalReceived < sendMessages * (maxRedeliveryCount + 1));
+
+        int totalInDeadLetter = 0;
+        do {
+            Message<byte[]> message = deadLetterConsumer.receive();
+            log.info("dead letter consumer received message : {} {}", message.getMessageId(), new String(message.getData()));
+            deadLetterConsumer.acknowledge(message);
+            totalInDeadLetter++;
+        } while (totalInDeadLetter < sendMessages);
+
+        deadLetterConsumer.close();
+        consumer.close();
+
+        Consumer<byte[]> checkConsumer = this.pulsarClient.newConsumer(Schema.BYTES)
+                .topic(topic)
+                .subscriptionName(subscriptionName)
+                .subscriptionType(SubscriptionType.Shared)
+                .subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
+                .subscribe();
+
+        Message<byte[]> checkMessage = checkConsumer.receive(3, TimeUnit.SECONDS);
+        if (checkMessage != null) {
+            log.info("check consumer received message : {} {}", checkMessage.getMessageId(), new String(checkMessage.getData()));
+        }
+        assertNull(checkMessage);
+
+        checkConsumer.close();
+    }
+
     /**
      * Retry topic feature relies on the delay queue feature when consumer produce a delayed message
      * to the retry topic. The delay queue feature is only supported in shared and key-shared subscription type.