GH-3693: Remove outdated DLT Topic Suffix references from Javadoc, reference doc and code sample.

Author: Alexis SEGURA

samples/sample-01/src/main/java/com/example/Application.java

@@ -79,7 +79,7 @@ public void listen(Foo2 foo) {
 		this.exec.execute(() -> System.out.println("Hit Enter to terminate..."));
 	}
 
-	@KafkaListener(id = "dltGroup", topics = "topic1.DLT")
+	@KafkaListener(id = "dltGroup", topics = "topic1-dlt")
 	public void dltListen(byte[] in) {
 		logger.info("Received from DLT: " + new String(in));
 		this.exec.execute(() -> System.out.println("Hit Enter to terminate..."));
@@ -92,7 +92,7 @@ public NewTopic topic() {
 
 	@Bean
 	public NewTopic dlt() {
-		return new NewTopic("topic1.DLT", 1, (short) 1);
+		return new NewTopic("topic1-dlt", 1, (short) 1);
 	}
 
 	@Bean

spring-kafka-docs/src/main/antora/modules/ROOT/pages/kafka/annotation-error-handling.adoc

@@ -743,7 +743,7 @@ public ErrorHandler eh(KafkaOperations<String, String> template) {
                     retries.value()[0]++;
                 }
                 return retries.value()[0] > 5
-                        ? new TopicPartition("topic.DLT", rec.partition())
+                        ? new TopicPartition("topic-dlt", rec.partition())
                         : new TopicPartition("topic", rec.partition());
             }), new FixedBackOff(0L, 0L));
 }

spring-kafka/src/main/java/org/springframework/kafka/listener/DeadLetterPublishingRecoverer.java

@@ -140,7 +140,7 @@ public class DeadLetterPublishingRecoverer extends ExceptionClassifier implement
 
 	/**
 	 * Create an instance with the provided template and a default destination resolving
-	 * function that returns a TopicPartition based on the original topic (appended with ".DLT")
+	 * function that returns a TopicPartition based on the original topic (appended with "-dlt")
 	 * from the failed record, and the same partition as the failed record. Therefore the
 	 * dead-letter topic must have at least as many partitions as the original topic.
 	 * @param template the {@link KafkaOperations} to use for publishing.
@@ -165,7 +165,7 @@ public DeadLetterPublishingRecoverer(KafkaOperations<? extends Object, ? extends
 	/**
 	 * Create an instance with the provided templates and a default destination resolving
 	 * function that returns a TopicPartition based on the original topic (appended with
-	 * ".DLT") from the failed record, and the same partition as the failed record.
+	 * "-dlt") from the failed record, and the same partition as the failed record.
 	 * Therefore the dead-letter topic must have at least as many partitions as the
 	 * original topic. The templates map keys are classes and the value the corresponding
 	 * template to use for objects (producer record values) of that type. A