Add Kotlin Hello World sample for Spring Integration

basic/helloworld-groovy/src/main/groovy/org/springframework/integration/samples/helloworld/HelloWorldConfig.groovy

@@ -43,7 +43,7 @@ class HelloWorldConfig {
 
 	@Bean
 	MessageChannel outputChannel() {
-		new QueueChannel(10)
+		new QueueChannel()
 	}
 
 	@Bean

basic/helloworld-kotlin/README.md

@@ -0,0 +1,38 @@
+Hello World Sample
+==================
+
+This is the Kotlin version of the helloworld Java sample using Kotlin DSL. This sample project contains 2 basic sample applications:
+
+* Hello World
+* Poller Application
+
+## Hello World
+
+The Hello World application demonstrates a simple message flow represented by the diagram below:
+
+    Message -> Channel -> ServiceActivator -> QueueChannel
+
+To run the sample simply execute **HelloWorldApp** in package **org.springframework.integration.samples.helloworld**.
+You can also execute that class using the [Gradle](https://www.gradle.org):
+
+    $ gradlew :helloworld-kotlin:runHelloWorldApp
+
+You should see the following output:
+
+    INFO : org.springframework.integration.samples.helloworld.HelloWorldApp - ==> HelloWorldDemo: Hello World
+
+## Poller Application
+
+This simple application will print out the current system time twice every 20 seconds.
+
+More specifically, an **Inbound Channel Adapter** polls for the current system time 2 times every 20 seconds (20000 milliseconds). The resulting message contains as payload the time in milliseconds and the message is sent to a **Logging Channel Adapter**, which will print the time to the command prompt.
+
+To run the sample simply execute **PollerApp** in package **org.springframework.integration.samples.helloworld**.
+You can also execute that class using the [Gradle](https://www.gradle.org):
+
+    $ gradlew :helloworld-kotlin:runPollerApp
+
+You should see output like the following:
+
+[task-scheduler-1][org.springframework.integration.samples.helloworld] GenericMessage [payload=1763478785243, headers={id=8f93b18a-063a-5e9f-4708-2ed1d04a1566, timestamp=1763478785244}]
+[task-scheduler-1][org.springframework.integration.samples.helloworld] GenericMessage [payload=1763478785248, headers={id=aa37e9c4-95d1-538c-a6cd-d400bb1474bf, timestamp=1763478785248}]

basic/helloworld-kotlin/pom.xml

@@ -0,0 +1,241 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.springframework.integration.samples</groupId>
+  <artifactId>helloworld-kotlin</artifactId>
+  <version>7.0.0</version>
+  <url>https://github.com/spring-projects/spring-integration-samples</url>
+  <organization>
+    <name>Spring IO</name>
+    <url>https://spring.io/projects/spring-integration</url>
+  </organization>
+  <licenses>
+    <license>
+      <name>Apache License, Version 2.0</name>
+      <url>https://www.apache.org/licenses/LICENSE-2.0.txt</url>
+      <distribution>repo</distribution>
+    </license>
+  </licenses>
+  <developers>
+    <developer>
+      <id>artembilan</id>
+      <name>Artem Bilan</name>
+      <email>artem.bilan@broadcom.com</email>
+      <roles>
+        <role>project lead</role>
+      </roles>
+    </developer>
+    <developer>
+      <id>garyrussell</id>
+      <name>Gary Russell</name>
+      <email>github@gprussell.net</email>
+      <roles>
+        <role>project lead emeritus</role>
+      </roles>
+    </developer>
+    <developer>
+      <id>markfisher</id>
+      <name>Mark Fisher</name>
+      <email>mark.ryan.fisher@gmail.com</email>
+      <roles>
+        <role>project founder and lead emeritus</role>
+      </roles>
+    </developer>
+    <developer>
+      <id>cppwfs</id>
+      <name>Glenn Renfro</name>
+      <email>glenn.renfro@broadcom.com</email>
+      <roles>
+        <role>project committer</role>
+      </roles>
+    </developer>
+  </developers>
+  <scm>
+    <connection>scm:git:scm:git:git://github.com/spring-projects/spring-integration-samples.git</connection>
+    <developerConnection>scm:git:scm:git:ssh://git@github.com:spring-projects/spring-integration-samples.git</developerConnection>
+    <url>https://github.com/spring-projects/spring-integration-samples</url>
+  </scm>
+  <issueManagement>
+    <system>GitHub</system>
+    <url>https://github.com/spring-projects/spring-integration-samples/issues</url>
+  </issueManagement>
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>org.jetbrains.kotlin</groupId>
+        <artifactId>kotlin-stdlib</artifactId>
+        <version>2.2.21</version>
+      </dependency>
+      <dependency>
+        <groupId>org.jetbrains.kotlin</groupId>
+        <artifactId>kotlin-reflect</artifactId>
+        <version>2.2.21</version>
+      </dependency>
+      <dependency>
+        <groupId>org.junit</groupId>
+        <artifactId>junit-bom</artifactId>
+        <version>6.0.0</version>
+        <scope>import</scope>
+        <type>pom</type>
+      </dependency>
+      <dependency>
+        <groupId>tools.jackson</groupId>
+        <artifactId>jackson-bom</artifactId>
+        <version>3.0.0-rc9</version>
+        <scope>import</scope>
+        <type>pom</type>
+      </dependency>
+      <dependency>
+        <groupId>com.fasterxml.jackson</groupId>
+        <artifactId>jackson-bom</artifactId>
+        <version>2.20.0</version>
+        <scope>import</scope>
+        <type>pom</type>
+      </dependency>
+      <dependency>
+        <groupId>org.springframework</groupId>
+        <artifactId>spring-framework-bom</artifactId>
+        <version>7.0.0-SNAPSHOT</version>
+        <scope>import</scope>
+        <type>pom</type>
+      </dependency>
+      <dependency>
+        <groupId>org.springframework.integration</groupId>
+        <artifactId>spring-integration-bom</artifactId>
+        <version>7.0.0-SNAPSHOT</version>
+        <scope>import</scope>
+        <type>pom</type>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.logging.log4j</groupId>
+      <artifactId>log4j-core</artifactId>
+      <version>2.24.3</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.integration</groupId>
+      <artifactId>spring-integration-core</artifactId>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.jetbrains.kotlin</groupId>
+      <artifactId>kotlin-stdlib</artifactId>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.jetbrains.kotlin</groupId>
+      <artifactId>kotlin-reflect</artifactId>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.hamcrest</groupId>
+      <artifactId>hamcrest-library</artifactId>
+      <version>2.2</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <version>5.18.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.integration</groupId>
+      <artifactId>spring-integration-test</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.logging.log4j</groupId>
+      <artifactId>log4j-core-test</artifactId>
+      <version>2.24.3</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.awaitility</groupId>
+      <artifactId>awaitility</artifactId>
+      <version>4.2.2</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.assertj</groupId>
+      <artifactId>assertj-core</artifactId>
+      <version>3.27.6</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-engine</artifactId>
+      <scope>runtime</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.platform</groupId>
+      <artifactId>junit-platform-launcher</artifactId>
+      <scope>runtime</scope>
+    </dependency>
+  </dependencies>
+  <properties>
+    <java.version>17</java.version>
+  </properties>
+  <repositories>
+    <repository>
+      <id>repo.spring.io.milestone</id>
+      <name>Spring Framework Maven Milestone Repository</name>
+      <url>https://repo.spring.io/milestone</url>
+    </repository>
+    <repository>
+      <id>repo.spring.io.snapshot</id>
+      <name>Spring Framework Maven Snapshot Repository</name>
+      <url>https://repo.spring.io/snapshot</url>
+    </repository>
+  </repositories>
+  <build>
+    <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
+    <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
+    <plugins>
+      <plugin>
+        <groupId>org.jetbrains.kotlin</groupId>
+        <artifactId>kotlin-maven-plugin</artifactId>
+        <version>2.2.21</version>
+        <configuration>
+          <args>
+            <arg>-Xjsr305=strict</arg>
+          </args>
+          <compilerPlugins>
+            <plugin>spring</plugin>
+          </compilerPlugins>
+        </configuration>
+        <executions>
+          <execution>
+            <id>compile</id>
+            <phase>compile</phase>
+            <goals>
+              <goal>compile</goal>
+            </goals>
+          </execution>
+          <execution>
+            <id>test-compile</id>
+            <phase>test-compile</phase>
+            <goals>
+              <goal>test-compile</goal>
+            </goals>
+          </execution>
+        </executions>
+        <dependencies>
+          <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-maven-allopen</artifactId>
+            <version>2.2.21</version>
+          </dependency>
+        </dependencies>
+      </plugin>
+    </plugins>
+  </build>
+</project>

basic/helloworld-kotlin/src/main/kotlin/org/springframework/integration/samples/helloworld/HelloService.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2025-present 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.integration.samples.helloworld
+
+/**
+ * Simple POJO to be referenced from a Service Activator.
+ *
+ * @author Glenn Renfro
+ */
+class HelloService {
+
+    fun sayHello(name: String) = "Hello $name"
+
+}

basic/helloworld-kotlin/src/main/kotlin/org/springframework/integration/samples/helloworld/HelloWorldApp.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2025-present 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.integration.samples.helloworld
+
+import org.apache.commons.logging.LogFactory
+import org.springframework.context.annotation.AnnotationConfigApplicationContext
+import org.springframework.messaging.MessageChannel
+import org.springframework.messaging.PollableChannel
+import org.springframework.messaging.support.GenericMessage
+
+/**
+ * Demonstrates a basic Message Endpoint that simply prepends a greeting
+ * ("Hello ") to an inbound String payload from a Message.
+ *
+ * @author Glenn Renfro
+ */
+object HelloWorldApp {
+
+    private val logger = LogFactory.getLog(HelloWorldApp::class.java)
+
+    @JvmStatic
+    fun main(args: Array<String>) {
+        val context = AnnotationConfigApplicationContext(HelloWorldConfig::class.java)
+        val inputChannel = context.getBean("inputChannel", MessageChannel::class.java)
+        val outputChannel = context.getBean("outputChannel", PollableChannel::class.java)
+        inputChannel.send(GenericMessage("World"))
+        logger.info("==> HelloWorldDemo: ${outputChannel.receive(0)?.payload}")
+        context.close()
+    }
+
+}