Make MQTT modules as auto-config

* Fix all the Checkstyle violations for those modules
* Introduce a `MosquittoContainerTest` contract into the `spring-function-test-support`
and use it in the MQTT modules
* Fix READMEs for previously migrated modules to auto-configuration

common/spring-function-test-support/src/main/java/org/springframework/cloud/fn/test/support/mqtt/MosquittoContainerTest.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2021-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.fn.test.support.mqtt;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+/**
+ * The base contract for JUnit tests based on the container for MQTT Mosquitto broker. The
+ * Testcontainers 'reuse' option must be disabled,so, Ryuk container is started and will
+ * clean all the containers up from this test suite after JVM exit. Since the Mosquitto
+ * container instance is shared via static property, it is going to be started only once
+ * per JVM, therefore the target Docker container is reused automatically.
+ *
+ * @author Artem Bilan
+ */
+@Testcontainers(disabledWithoutDocker = true)
+public interface MosquittoContainerTest {
+
+	GenericContainer<?> MOSQUITTO_CONTAINER = new GenericContainer<>("eclipse-mosquitto:2.0.13")
+		.withCommand("mosquitto -c /mosquitto-no-auth.conf")
+		.withExposedPorts(1883);
+
+	@BeforeAll
+	static void startContainer() {
+		MOSQUITTO_CONTAINER.start();
+	}
+
+	static String mqttUrl() {
+		return "tcp://localhost:" + MOSQUITTO_CONTAINER.getFirstMappedPort();
+	}
+
+}

common/spring-function-test-support/src/main/java/org/springframework/cloud/fn/test/support/mqtt/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The MQTT protocol testing support.
+ */
+package org.springframework.cloud.fn.test.support.mqtt;

common/spring-mqtt-common/src/main/java/org/springframework/cloud/fn/common/mqtt/MqttConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 the original author or authors.
+ * Copyright 2017-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,28 +23,25 @@
 import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
 import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence;
 
-import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
 import org.springframework.integration.mqtt.core.DefaultMqttPahoClientFactory;
 import org.springframework.integration.mqtt.core.MqttPahoClientFactory;
 import org.springframework.util.ObjectUtils;
 
 /**
- * Generic mqtt configuration.
+ * The MQTT client auto-configuration.
  *
  * @author Janne Valkealahti
  * @author Artem Bilan
  */
-@Configuration
+@AutoConfiguration
+@EnableConfigurationProperties(MqttProperties.class)
 public class MqttConfiguration {
 
-	@Autowired
-	private MqttProperties mqttProperties;
-
 	@Bean
-	public MqttPahoClientFactory mqttClientFactory() {
-
+	public MqttPahoClientFactory mqttClientFactory(MqttProperties mqttProperties) {
 		MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
 		mqttConnectOptions.setServerURIs(mqttProperties.getUrl());
 		mqttConnectOptions.setUserName(mqttProperties.getUsername());

common/spring-mqtt-common/src/main/java/org/springframework/cloud/fn/common/mqtt/MqttProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 the original author or authors.
+ * Copyright 2017-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +25,7 @@
 import org.springframework.validation.annotation.Validated;
 
 /**
- * Generic mqtt connection properties.
+ * The MQTT client properties.
  *
  * @author Janne Valkealahti
  * @author Artem Bilan
@@ -81,63 +81,63 @@ public class MqttProperties {
 
 	@Size(min = 1)
 	public String[] getUrl() {
-		return url;
+		return this.url;
 	}
 
 	public void setUrl(String[] url) {
 		this.url = url;
 	}
 
 	public String getUsername() {
-		return username;
+		return this.username;
 	}
 
 	public void setUsername(String username) {
 		this.username = username;
 	}
 
 	public String getPassword() {
-		return password;
+		return this.password;
 	}
 
 	public void setPassword(String password) {
 		this.password = password;
 	}
 
 	public boolean isCleanSession() {
-		return cleanSession;
+		return this.cleanSession;
 	}
 
 	public void setCleanSession(boolean cleanSession) {
 		this.cleanSession = cleanSession;
 	}
 
 	public int getKeepAliveInterval() {
-		return keepAliveInterval;
+		return this.keepAliveInterval;
 	}
 
 	public void setKeepAliveInterval(int keepAliveInterval) {
 		this.keepAliveInterval = keepAliveInterval;
 	}
 
 	public int getConnectionTimeout() {
-		return connectionTimeout;
+		return this.connectionTimeout;
 	}
 
 	public void setConnectionTimeout(int connectionTimeout) {
 		this.connectionTimeout = connectionTimeout;
 	}
 
 	public String getPersistence() {
-		return persistence;
+		return this.persistence;
 	}
 
 	public void setPersistence(String persistence) {
 		this.persistence = persistence;
 	}
 
 	public String getPersistenceDirectory() {
-		return persistenceDirectory;
+		return this.persistenceDirectory;
 	}
 
 	public void setPersistenceDirectory(String persistenceDirectory) {

common/spring-mqtt-common/src/main/java/org/springframework/cloud/fn/common/mqtt/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The MQTT client auto-configuration support.
+ */
+package org.springframework.cloud.fn.common.mqtt;

common/spring-mqtt-common/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -0,0 +1 @@
+org.springframework.cloud.fn.common.mqtt.MqttConfiguration

consumer/spring-file-consumer/README.adoc

@@ -5,7 +5,7 @@ The consumer uses the `FileWritingMessageHandler` from Spring Integration.
 
 ## Beans for injection
 
-You can import `FileConsumerConfiguration` in the application and then inject the following bean.
+The `FileConsumerConfiguration` auto-configuration provides the following bean:
 
 `Consumer<Message<?>> fileConsumer`
 

consumer/spring-ftp-consumer/README.adoc

@@ -5,7 +5,7 @@ The consumer uses the `FtpMessageHandler` from Spring Integration.
 
 ## Beans for injection
 
-You can import `FtpConsumerConfiguration` in the application and then inject the following bean.
+The `FtpConsumerConfiguration` auto-configuration provides the following bean:
 
 `Consumer<Message<?>> ftpConsumer`
 

consumer/spring-mqtt-consumer/README.adoc

@@ -4,7 +4,7 @@ A consumer that allows you to send messages using the MQTT protocol.
 
 ## Beans for injection
 
-You can import `MqttConsumerConfiguration` in the application and then inject the following bean.
+The `MqttConsumerConfiguration` auto-configuration provides the following bean:
 
 `Consumer<Message<?>> mqttConsumer`
 

consumer/spring-mqtt-consumer/build.gradle

@@ -1,3 +1,5 @@
 dependencies {
     api project(':spring-mqtt-common')
+
+    testImplementation project(':spring-function-test-support')
 }

consumer/spring-mqtt-consumer/src/main/java/org/springframework/cloud/fn/consumer/mqtt/MqttConsumerConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2022 the original author or authors.
+ * Copyright 2017-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,14 +19,11 @@
 import java.util.function.Consumer;
 
 import org.springframework.beans.factory.BeanFactory;
-import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.fn.common.config.ComponentCustomizer;
 import org.springframework.cloud.fn.common.mqtt.MqttConfiguration;
-import org.springframework.cloud.fn.common.mqtt.MqttProperties;
 import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.Import;
 import org.springframework.integration.mqtt.core.MqttPahoClientFactory;
 import org.springframework.integration.mqtt.outbound.MqttPahoMessageHandler;
 import org.springframework.integration.mqtt.support.DefaultPahoMessageConverter;
@@ -35,45 +32,37 @@
 import org.springframework.messaging.MessageHandler;
 
 /**
- * A consumer that sends data to Mqtt.
+ * A consumer that sends data to MQTT.
  *
  * @author Janne Valkealahti
- *
+ * @author Artem Bilan
  */
-@Configuration(proxyBeanMethods = false)
-@EnableConfigurationProperties({ MqttProperties.class, MqttConsumerProperties.class })
-@Import(MqttConfiguration.class)
+@EnableConfigurationProperties(MqttConsumerProperties.class)
+@AutoConfiguration(after = MqttConfiguration.class)
 public class MqttConsumerConfiguration {
 
-	@Autowired
-	private MqttConsumerProperties properties;
-
-	@Autowired
-	private MqttPahoClientFactory mqttClientFactory;
-
-	@Autowired
-	private BeanFactory beanFactory;
-
 	@Bean
 	public Consumer<Message<?>> mqttConsumer(MessageHandler mqttOutbound) {
 		return mqttOutbound::handleMessage;
 	}
 
 	@Bean
-	public MessageHandler mqttOutbound(
+	public MessageHandler mqttOutbound(MqttConsumerProperties properties, MqttPahoClientFactory mqttClientFactory,
+			BeanFactory beanFactory,
 			@Nullable ComponentCustomizer<MqttPahoMessageHandler> mqttMessageHandlerCustomizer) {
 
 		MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler(properties.getClientId(), mqttClientFactory);
 		messageHandler.setAsync(properties.isAsync());
 		messageHandler.setDefaultTopic(properties.getTopic());
-		messageHandler.setConverter(pahoMessageConverter());
+		messageHandler.setConverter(pahoMessageConverter(properties, beanFactory));
 		if (mqttMessageHandlerCustomizer != null) {
 			mqttMessageHandlerCustomizer.customize(messageHandler);
 		}
 		return messageHandler;
 	}
 
-	public DefaultPahoMessageConverter pahoMessageConverter() {
+	private DefaultPahoMessageConverter pahoMessageConverter(MqttConsumerProperties properties,
+			BeanFactory beanFactory) {
 		DefaultPahoMessageConverter converter = new DefaultPahoMessageConverter(properties.getQos(),
 				properties.isRetained(), properties.getCharset());
 		converter.setBeanFactory(beanFactory);

consumer/spring-mqtt-consumer/src/main/java/org/springframework/cloud/fn/consumer/mqtt/MqttConsumerProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 the original author or authors.
+ * Copyright 2017-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
 import org.springframework.validation.annotation.Validated;
 
 /**
- * Properties for the Mqtt Consumer.
+ * Properties for the MQTT Consumer.
  *
  * @author Janne Valkealahti
  *
@@ -34,32 +34,32 @@
 public class MqttConsumerProperties {
 
 	/**
-	 * identifies the client.
+	 * Identifies the client.
 	 */
 	private String clientId = "stream.client.id.sink";
 
 	/**
-	 * the topic to which the sink will publish.
+	 * The topic to which the sink will publish.
 	 */
 	private String topic = "stream.mqtt";
 
 	/**
-	 * the quality of service to use.
+	 * The quality of service to use.
 	 */
 	private int qos = 1;
 
 	/**
-	 * whether to set the 'retained' flag.
+	 * Whether to set the 'retained' flag.
 	 */
 	private boolean retained = false;
 
 	/**
-	 * the charset used to convert a String payload to byte[].
+	 * The charset used to convert a String payload to byte[].
 	 */
 	private String charset = "UTF-8";
 
 	/**
-	 * whether or not to use async sends.
+	 * Whether to use async sends.
 	 */
 	private boolean async = false;
 

consumer/spring-mqtt-consumer/src/main/java/org/springframework/cloud/fn/consumer/mqtt/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The MQTT consumer auto-configuration support.
+ */
+package org.springframework.cloud.fn.consumer.mqtt;

consumer/spring-mqtt-consumer/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -0,0 +1 @@
+org.springframework.cloud.fn.consumer.mqtt.MqttConsumerConfiguration