Polish "Add option for configuring max messages per task"

See gh-42341

Author: snicoll

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jms/JmsProperties.java

@@ -187,7 +187,9 @@ public static class Listener {
 		private Duration receiveTimeout = Duration.ofSeconds(1);
 
 		/**
-		 * Specify the maximum number of messages to process in one task.
+		 * Specify the maximum number of messages to process in one task. By default,
+		 * unlimited unless a SchedulingTaskExecutor is configured on the listener (10
+		 * messages), as it indicates a preference for short-lived tasks.
 		 */
 		private Integer maxMessagesPerTask;
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jms/JmsAutoConfigurationTests.java

@@ -177,7 +177,7 @@ void testJmsListenerContainerFactoryWithCustomSettings() {
 					"spring.jms.listener.session.transacted=false", "spring.jms.listener.minConcurrency=2",
 					"spring.jms.listener.receiveTimeout=2s", "spring.jms.listener.maxConcurrency=10",
 					"spring.jms.subscription-durable=true", "spring.jms.client-id=exampleId",
-					"spring.jms.listener.max-messages-per-task=10")
+					"spring.jms.listener.max-messages-per-task=5")
 			.run(this::testJmsListenerContainerFactoryWithCustomSettings);
 	}
 
@@ -189,7 +189,7 @@ private void testJmsListenerContainerFactoryWithCustomSettings(AssertableApplica
 		assertThat(container.getConcurrentConsumers()).isEqualTo(2);
 		assertThat(container.getMaxConcurrentConsumers()).isEqualTo(10);
 		assertThat(container).hasFieldOrPropertyWithValue("receiveTimeout", 2000L);
-		assertThat(container).hasFieldOrPropertyWithValue("maxMessagesPerTask", 10);
+		assertThat(container).hasFieldOrPropertyWithValue("maxMessagesPerTask", 5);
 		assertThat(container.isSubscriptionDurable()).isTrue();
 		assertThat(container.getClientId()).isEqualTo("exampleId");
 	}