isPublisherConfirms in RabbitProperties should not throw NPE

Fixes gh-17967

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitProperties.java

@@ -278,7 +278,7 @@ public class RabbitProperties {
 	@DeprecatedConfigurationProperty(reason = "replaced to support additional confirm types",
 			replacement = "spring.rabbitmq.publisher-confirm-type")
 	public boolean isPublisherConfirms() {
-		return this.publisherConfirmType.equals(ConfirmType.CORRELATED);
+		return ConfirmType.CORRELATED.equals(this.publisherConfirmType);
 	}
 
 	@Deprecated

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/amqp/RabbitPropertiesTests.java

@@ -20,6 +20,7 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.amqp.rabbit.config.DirectRabbitListenerContainerFactory;
 import org.springframework.amqp.rabbit.config.SimpleRabbitListenerContainerFactory;
+import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
 import org.springframework.amqp.rabbit.listener.DirectMessageListenerContainer;
 import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
 
@@ -240,4 +241,24 @@ class RabbitPropertiesTests {
 		assertThat(container).hasFieldOrPropertyWithValue("missingQueuesFatal", direct.isMissingQueuesFatal());
 	}
 
+	@Test
+	@Deprecated
+	void isPublisherConfirmsShouldDefaultToFalse() {
+		assertThat(this.properties.isPublisherConfirms()).isEqualTo(false);
+	}
+
+	@Test
+	@Deprecated
+	void isPublisherConfirmsWhenPublisherConfirmsTypeSimpleShouldBeFalse() {
+		this.properties.setPublisherConfirmType(CachingConnectionFactory.ConfirmType.SIMPLE);
+		assertThat(this.properties.isPublisherConfirms()).isEqualTo(false);
+	}
+
+	@Test
+	@Deprecated
+	void isPublisherConfirmsWhenPublisherConfirmsTypeCorrelatedShouldBeTrue() {
+		this.properties.setPublisherConfirmType(CachingConnectionFactory.ConfirmType.CORRELATED);
+		assertThat(this.properties.isPublisherConfirms()).isEqualTo(true);
+	}
+
 }