GH-224: Fix SnsBodyBuilder usage in the Doc

Fixes #224

* Fix `SnsMessageBuilder` -> `SnsBodyBuilder` in the `SnsMessageHandler.onInit()` comment
for SpEL import registration
* Upgrade to Localstack `2.1.0`
* Rename `SnsMessageBuilderTests` -> `SnsBodyBuilderTests` for consistency of its purpose

Author: artembilan

README.md

@@ -333,7 +333,7 @@ The Java Config looks like:
 public MessageHandler snsMessageHandler() {
     SnsMessageHandler handler = new SnsMessageHandler(amazonSns());
     adapter.setTopicArn("arn:aws:sns:eu-west:123456789012:test");
-    String bodyExpression = "SnsBodyBuilder.withDefault(payload).forProtocols(payload.substring(0, 140), 'sms')";
+    String bodyExpression = "T(SnsBodyBuilder).withDefault(payload).forProtocols(payload.substring(0, 140), 'sms')";
     handler.setBodyExpression(spelExpressionParser.parseExpression(bodyExpression));
 
     // message-group ID and deduplication ID are used for FIFO topics

src/main/java/org/springframework/integration/aws/outbound/SnsMessageHandler.java

@@ -192,7 +192,7 @@ protected void onInit() {
 		if (typeLocator instanceof StandardTypeLocator) {
 			/*
 			 * Register the 'org.springframework.integration.aws.support' package you
-			 * don't need a FQCN for the 'SnsMessageBuilder'.
+			 * don't need a FQCN for the 'SnsBodyBuilder'.
 			 */
 			((StandardTypeLocator) typeLocator).registerImport("org.springframework.integration.aws.support");
 		}

src/test/java/org/springframework/integration/aws/LocalstackContainerTest.java

@@ -48,7 +48,7 @@
 public interface LocalstackContainerTest {
 
 	LocalStackContainer LOCAL_STACK_CONTAINER =
-			new LocalStackContainer(DockerImageName.parse("localstack/localstack:2.0.0"));
+			new LocalStackContainer(DockerImageName.parse("localstack/localstack:2.1.0"));
 
 	@BeforeAll
 	static void startContainer() {

src/test/java/org/springframework/integration/aws/outbound/SnsMessageBuilderTests.java renamed to src/test/java/org/springframework/integration/aws/outbound/SnsBodyBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 the original author or authors.
+ * Copyright 2016-2023 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.
@@ -26,10 +26,10 @@
 /**
  * @author Artem Bilan
  */
-class SnsMessageBuilderTests {
+class SnsBodyBuilderTests {
 
 	@Test
-	void testSnsMessageBuilder() {
+	void testSnsBodyBuilder() {
 		assertThatIllegalArgumentException()
 				.isThrownBy(() -> SnsBodyBuilder.withDefault(""))
 				.withMessageContaining("defaultMessage must not be empty.");