GH-3664: Re-enable JavaScript support via GraalVM (#3911)

* GH-3664: Re-enable JavaScript support via GraalVM

Fixes https://github.com/spring-projects/spring-integration/issues/3664

The JavaScript JSR223 engine has been removed from Java.

Migrate JavaScript support into GraalVM Polyglot API:
* Implement `PolyglotScriptExecutor` which can also support other GraalVM languages
* Change the `ScriptExecutorFactory` to use a `PolyglotScriptExecutor` when it encounters JavaScript
* Re-enable tests for JavaScript
* Add GraalVM Polyglot support into docs

* * Reinstate `@EnabledIfSystemProperty` for GraalVM JS system property

spring-integration-scripting/src/main/java/org/springframework/integration/scripting/PolyglotScriptExecutor.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2022 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.scripting;
+
+import java.util.Map;
+
+import org.graalvm.polyglot.Context;
+import org.graalvm.polyglot.Value;
+
+import org.springframework.lang.Nullable;
+import org.springframework.scripting.ScriptSource;
+import org.springframework.util.Assert;
+
+/**
+ * GraalVM Polyglot {@link ScriptExecutor} implementation.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+public class PolyglotScriptExecutor implements ScriptExecutor {
+
+	private final String language;
+
+	private Context.Builder contextBuilder;
+
+	/**
+	 * Construct an executor based on the provided language id.
+	 * @param language the supported by GraalVM language id.
+	 */
+	public PolyglotScriptExecutor(String language) {
+		this(language, Context.newBuilder().allowAllAccess(true));
+	}
+
+	/**
+	 * Construct an executor based on the provided language id.
+	 * @param language the supported by GraalVM language id.
+	 */
+	public PolyglotScriptExecutor(String language, Context.Builder contextBuilder) {
+		Assert.hasText(language, "'language' must not be empty");
+		Assert.notNull(contextBuilder, "'contextBuilder' must not be null");
+		this.contextBuilder = contextBuilder;
+		this.language = language;
+		try (Context context = this.contextBuilder.build()) {
+			context.initialize(language);
+		}
+	}
+
+	@Override
+	public Object executeScript(ScriptSource scriptSource, @Nullable Map<String, Object> variables) {
+		try (Context context = this.contextBuilder.build()) {
+			if (variables != null) {
+				Value bindings = context.getBindings(this.language);
+				variables.forEach(bindings::putMember);
+			}
+			return context.eval(this.language, scriptSource.getScriptAsString()).as(Object.class);
+		}
+		catch (Exception ex) {
+			throw new ScriptingException(ex.getMessage(), ex);
+		}
+	}
+
+}

spring-integration-scripting/src/main/java/org/springframework/integration/scripting/jsr223/ScriptExecutorFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -19,6 +19,7 @@ package org.springframework.integration.scripting.jsr223;
 import javax.script.ScriptEngine;
 import javax.script.ScriptEngineManager;
 
+import org.springframework.integration.scripting.PolyglotScriptExecutor;
 import org.springframework.integration.scripting.ScriptExecutor;
 import org.springframework.util.Assert;
 
@@ -42,6 +43,9 @@ public final class ScriptExecutorFactory {
 		else if (language.equalsIgnoreCase("kotlin")) {
 			return new KotlinScriptExecutor();
 		}
+		else if (language.equalsIgnoreCase("js") || language.equalsIgnoreCase("javascript")) {
+			return new PolyglotScriptExecutor("js");
+		}
 		return new DefaultScriptExecutor(language);
 	}
 
@@ -58,6 +62,9 @@ public final class ScriptExecutorFactory {
 		if (extension.equals("kts")) {
 			return "kotlin";
 		}
+		else if (extension.equals("js")) {
+			return "js";
+		}
 		ScriptEngineManager engineManager = new ScriptEngineManager();
 		ScriptEngine engine = engineManager.getEngineByExtension(extension);
 		Assert.state(engine != null, () -> "No suitable scripting engine found for extension '" + extension + "'");

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/config/jsr223/Jsr223HeaderEnricherTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/config/jsr223/Jsr223InboundChannelAdapterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2021 the original author or authors.
+ * Copyright 2013-2022 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.

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/config/jsr223/Jsr223TransformerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.