Make spring-task-launch-request-function as auto-config

* Also make a `spring-spel-function`, `spring-filter-function` as auto-config
* Fix Checkstyle violations in those module, as well as in the `spring-payload-converter-function`

function/spring-filter-function/README.adoc

@@ -4,7 +4,7 @@ This module provides a filter function that can be reused and composed in other
 
 ## Beans for injection
 
-You can import the `FilterFunctionConfiguration` in a Spring Boot application and then inject the following bean.
+The `FilterFunctionConfiguration` auto-configuration provides following bean:
 
 `filterFunction`
 

function/spring-filter-function/src/main/java/org/springframework/cloud/fn/filter/FilterFunctionConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -25,6 +25,8 @@
 import org.springframework.messaging.Message;
 
 /**
+ * Auto-configuration for Filter function.
+ *
  * @author Artem Bilan
  * @author David Turanski
  */
@@ -36,7 +38,7 @@ public class FilterFunctionConfiguration {
 	public Function<Message<?>, Message<?>> filterFunction(
 			ExpressionEvaluatingTransformer filterExpressionEvaluatingTransformer) {
 
-		return message -> {
+		return (message) -> {
 			if ((Boolean) filterExpressionEvaluatingTransformer.transform(message).getPayload()) {
 				return message;
 			}

function/spring-filter-function/src/main/java/org/springframework/cloud/fn/filter/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The Filter function support classes.
+ */
+package org.springframework.cloud.fn.filter;

function/spring-filter-function/src/test/java/org/springframework/cloud/fn/filter/FilterFunctionApplicationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -18,7 +18,6 @@
 
 import java.util.List;
 import java.util.function.Function;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Test;
@@ -47,9 +46,8 @@ public class FilterFunctionApplicationTests {
 
 	@Test
 	public void testFilter() {
-		Stream<Message<?>> messages = List.of("hello", "hello world").stream().map(GenericMessage::new);
-		List<Message<?>> result = messages.filter(message -> this.filter.apply(message) != null)
-			.collect(Collectors.toList());
+		Stream<Message<?>> messages = Stream.of("hello", "hello world").map(GenericMessage::new);
+		List<Message<?>> result = messages.filter((message) -> this.filter.apply(message) != null).toList();
 		assertThat(result.size()).isEqualTo(1);
 		assertThat(result.get(0).getPayload()).isNotNull();
 		assertThat(result.get(0).getPayload()).isEqualTo("hello world");

function/spring-payload-converter-function/src/main/java/functions/ByteArrayTextToString.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -24,6 +24,8 @@
 import org.springframework.util.MimeTypeUtils;
 
 /**
+ * The function which transforms a byte array to string.
+ *
  * @author Christian Tzolov
  */
 public class ByteArrayTextToString implements Function<Message<?>, Message<?>> {

function/spring-payload-converter-function/src/main/java/functions/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The utility functions for common usage.
+ */
+package functions;

function/spring-spel-function/README.adoc

@@ -5,7 +5,7 @@ The function can be used to apply SpEL transformations on data based on a SpEL e
 
 ## Beans for injection
 
-You can import the `SpelFunctionConfiguration` in a Spring Boot application and then inject the following bean.
+The `SpelFunctionConfiguration` auto-configuration provides the following bean:
 
 `spelFunction`
 

function/spring-spel-function/src/main/java/org/springframework/cloud/fn/spel/SpelFunctionConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -18,30 +18,33 @@
 
 import java.util.function.Function;
 
+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.expression.spel.standard.SpelExpressionParser;
 import org.springframework.integration.transformer.ExpressionEvaluatingTransformer;
 import org.springframework.messaging.Message;
 
-@Configuration
+/**
+ * Auto-configuration for SpEL function.
+ *
+ * @author Soby Chacko
+ */
+@AutoConfiguration
 @EnableConfigurationProperties(SpelFunctionProperties.class)
 public class SpelFunctionConfiguration {
 
 	@Bean
 	public Function<Message<?>, Message<?>> spelFunction(
 			ExpressionEvaluatingTransformer expressionEvaluatingTransformer) {
 
-		return message -> expressionEvaluatingTransformer.transform(message);
+		return expressionEvaluatingTransformer::transform;
 	}
 
 	@Bean
 	public ExpressionEvaluatingTransformer expressionEvaluatingTransformer(
 			SpelFunctionProperties spelFunctionProperties) {
 
-		return new ExpressionEvaluatingTransformer(
-				new SpelExpressionParser().parseExpression(spelFunctionProperties.getExpression()));
+		return new ExpressionEvaluatingTransformer(spelFunctionProperties.getExpression());
 	}
 
 }

function/spring-spel-function/src/main/java/org/springframework/cloud/fn/spel/SpelFunctionProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -18,7 +18,8 @@
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.expression.Expression;
-import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.integration.expression.FunctionExpression;
+import org.springframework.messaging.Message;
 
 /**
  * Configuration properties for the SpEL function.
@@ -29,18 +30,18 @@
 @ConfigurationProperties("spel.function")
 public class SpelFunctionProperties {
 
-	private static final Expression DEFAULT_EXPRESSION = new SpelExpressionParser().parseExpression("payload");
+	private static final Expression DEFAULT_EXPRESSION = new FunctionExpression<Message<?>>(Message::getPayload);
 
 	/**
 	 * A SpEL expression to apply.
 	 */
-	private String expression = DEFAULT_EXPRESSION.getExpressionString();
+	private Expression expression = DEFAULT_EXPRESSION;
 
-	public String getExpression() {
+	public Expression getExpression() {
 		return this.expression;
 	}
 
-	public void setExpression(String expression) {
+	public void setExpression(Expression expression) {
 		this.expression = expression;
 	}
 

function/spring-spel-function/src/main/java/org/springframework/cloud/fn/spel/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The SpEL function auto-configuration support.
+ */
+package org.springframework.cloud.fn.spel;

function/spring-task-launch-request-function/README.adoc

@@ -1,11 +1,11 @@
 # Task Launch Request Function
 
 This module provides a function that can be reused and composed in other applications to transform the output to a link:src/main/java/org/springframework/cloud/fn/task/launch/request/TaskLaunchRequest.java[TaskLaunchRequest]
-that can be used as input to the Tasklauncher function to launch a task.
+that can be used as input to the TaskLauncher function to launch a task.
 
 ## Beans for injection
 
-You can import the `TaskLaunchRequestFunctionConfiguration` in a Spring Boot application and then inject the following bean.
+The `TaskLaunchRequestFunctionConfiguration` auto-configuration provides the following bean:
 
 `taskLaunchRequestFunction` as a link:src/main/java/org/springframework/cloud/fn/task/launch/request/TaskLaunchRequestFunction.java[TaskLaunchRequestFunction].
 

function/spring-task-launch-request-function/src/main/java/org/springframework/cloud/fn/task/launch/request/TaskLaunchRequestFunctionConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -23,14 +23,14 @@
 import java.util.List;
 import java.util.Map;
 
-import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
-import org.springframework.integration.expression.ExpressionUtils;
+import org.springframework.integration.context.IntegrationContextUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.util.StringUtils;
@@ -40,11 +40,11 @@
  * that can be composed with other Suppliers or Functions to transform any {@link Message}
  * to a {@link TaskLaunchRequest} which may be used as input to the
  * {@code TaskLauncherFunction} to launch a task.
- *
+ * <p>
  * Command line arguments used by the task, as well as the task name itself may be
  * statically configured or extracted from the message contents, using SpEL. See
  * {@link TaskLaunchRequestFunctionProperties} for details.
- *
+ * <p>
  * It is also possible to provide your own implementations of
  * {@link CommandLineArgumentsMessageMapper} and {@link TaskNameMessageMapper}.
  *
@@ -57,7 +57,7 @@ public class TaskLaunchRequestFunctionConfiguration {
 	/**
 	 * The function name.
 	 */
-	public final static String TASK_LAUNCH_REQUEST_FUNCTION_NAME = "taskLaunchRequestFunction";
+	public static final String TASK_LAUNCH_REQUEST_FUNCTION_NAME = "taskLaunchRequestFunction";
 
 	/**
 	 * A {@link java.util.function.Function} to transform a {@link Message} payload to a
@@ -67,22 +67,24 @@ public class TaskLaunchRequestFunctionConfiguration {
 	 * @return a {@code TaskLaunchRequest} Message.
 	 */
 	@Bean(name = TASK_LAUNCH_REQUEST_FUNCTION_NAME)
-	public TaskLaunchRequestFunction taskLaunchRequest(
-			TaskLaunchRequestMessageProcessor taskLaunchRequestMessageProcessor) {
-		return message -> taskLaunchRequestMessageProcessor.postProcessMessage(message);
+	TaskLaunchRequestFunction taskLaunchRequest(TaskLaunchRequestMessageProcessor taskLaunchRequestMessageProcessor) {
+
+		return taskLaunchRequestMessageProcessor::postProcessMessage;
 	}
 
 	@Bean
-	public TaskLaunchRequestSupplier taskLaunchRequestInitializer(
+	TaskLaunchRequestSupplier taskLaunchRequestInitializer(
 			TaskLaunchRequestFunctionProperties taskLaunchRequestProperties) {
+
 		return new TaskLaunchRequestPropertiesInitializer(taskLaunchRequestProperties);
 	}
 
 	@SuppressWarnings("SpringJavaInjectionPointsAutowiringInspection")
 	@Bean
-	public TaskLaunchRequestMessageProcessor taskLaunchRequestMessageProcessor(
+	TaskLaunchRequestMessageProcessor taskLaunchRequestMessageProcessor(
 			TaskLaunchRequestSupplier taskLaunchRequestInitializer, TaskLaunchRequestFunctionProperties properties,
-			EvaluationContext evaluationContext, @Nullable TaskNameMessageMapper taskNameMessageMapper,
+			@Qualifier(IntegrationContextUtils.INTEGRATION_EVALUATION_CONTEXT_BEAN_NAME) EvaluationContext evaluationContext,
+			@Nullable TaskNameMessageMapper taskNameMessageMapper,
 			@Nullable CommandLineArgumentsMessageMapper commandLineArgumentsMessageMapper) {
 
 		if (taskNameMessageMapper == null) {
@@ -97,26 +99,23 @@ public TaskLaunchRequestMessageProcessor taskLaunchRequestMessageProcessor(
 				commandLineArgumentsMessageMapper);
 	}
 
-	@Bean
-	public EvaluationContext evaluationContext(BeanFactory beanFactory) {
-		return ExpressionUtils.createStandardEvaluationContext(beanFactory);
-	}
-
 	private TaskNameMessageMapper taskNameMessageMapper(TaskLaunchRequestFunctionProperties taskLaunchRequestProperties,
 			EvaluationContext evaluationContext) {
+
 		if (StringUtils.hasText(taskLaunchRequestProperties.getTaskNameExpression())) {
 			SpelExpressionParser expressionParser = new SpelExpressionParser();
 			Expression taskNameExpression = expressionParser
 				.parseExpression(taskLaunchRequestProperties.getTaskNameExpression());
 			return new ExpressionEvaluatingTaskNameMessageMapper(taskNameExpression, evaluationContext);
 		}
 
-		return message -> taskLaunchRequestProperties.getTaskName();
+		return (message) -> taskLaunchRequestProperties.getTaskName();
 	}
 
 	private CommandLineArgumentsMessageMapper commandLineArgumentsMessageMapper(
 			TaskLaunchRequestFunctionProperties taskLaunchRequestFunctionProperties,
 			EvaluationContext evaluationContext) {
+
 		return new ExpressionEvaluatingCommandLineArgsMapper(taskLaunchRequestFunctionProperties.getArgExpressions(),
 				evaluationContext);
 	}
@@ -130,25 +129,17 @@ private static class TaskLaunchRequestPropertiesInitializer extends TaskLaunchRe
 			this.deploymentPropertiesSupplier(() -> KeyValueListParser
 				.parseCommaDelimitedKeyValuePairs(taskLaunchRequestProperties.getDeploymentProperties()));
 
-			this.taskNameSupplier(() -> taskLaunchRequestProperties.getTaskName());
+			this.taskNameSupplier(taskLaunchRequestProperties::getTaskName);
 		}
 
 	}
 
-	private static class ExpressionEvaluatingTaskNameMessageMapper implements TaskNameMessageMapper {
-
-		private final Expression expression;
-
-		private final EvaluationContext evaluationContext;
-
-		ExpressionEvaluatingTaskNameMessageMapper(Expression expression, EvaluationContext evaluationContext) {
-			this.evaluationContext = evaluationContext;
-			this.expression = expression;
-		}
+	private record ExpressionEvaluatingTaskNameMessageMapper(Expression expression,
+			EvaluationContext evaluationContext) implements TaskNameMessageMapper {
 
 		@Override
 		public String processMessage(Message<?> message) {
-			return expression.getValue(evaluationContext, message).toString();
+			return this.expression.getValue(this.evaluationContext, message).toString();
 		}
 
 	}
@@ -166,7 +157,7 @@ private static class ExpressionEvaluatingCommandLineArgsMapper implements Comman
 				SpelExpressionParser expressionParser = new SpelExpressionParser();
 
 				KeyValueListParser.parseCommaDelimitedKeyValuePairs(argExpressions)
-					.forEach((k, v) -> argExpressionsMap.put(k, expressionParser.parseExpression(v)));
+					.forEach((k, v) -> this.argExpressionsMap.put(k, expressionParser.parseExpression(v)));
 			}
 		}
 

function/spring-task-launch-request-function/src/main/java/org/springframework/cloud/fn/task/launch/request/TaskLaunchRequestFunctionProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2020 the original author or authors.
+ * Copyright 2020-2024 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.
@@ -82,23 +82,23 @@ public void setDeploymentProperties(String deploymentProperties) {
 	}
 
 	public String getTaskName() {
-		return taskName;
+		return this.taskName;
 	}
 
 	public void setTaskName(String taskName) {
 		this.taskName = taskName;
 	}
 
 	public String getTaskNameExpression() {
-		return taskNameExpression;
+		return this.taskNameExpression;
 	}
 
 	public void setTaskNameExpression(String taskNameExpression) {
 		this.taskNameExpression = taskNameExpression;
 	}
 
 	public String getArgExpressions() {
-		return argExpressions;
+		return this.argExpressions;
 	}
 
 	public void setArgExpressions(String argExpressions) {