docs: HelloWorldStreamFunction in examples fails with sam (#1532)

* Setting up Kotlin environment. Converting test to Kotlin.

* Deploying via SAM successfully.

* Added Kotlin example.

* Removing unused Gradle build file.

* Adding SAM template so can be used as an existing project and Java target compatibility

* Adding SAM template so can be used as an existing project

* Updating guidance to use SAM for build and deploy

* Restructuring separate Java and Kotlin examples.

* Updating core examples readme to represent new structure for Java and Kotlin examples.

* Refactoring application code for efficiency, updating build to cover tests too and is more idiomatic and readme to be more descriptive

* Updating to fix trailing \n

* Updating guidance to be more specific for examples

* Adopting new mechanism for specifying jvm target.

* accommodating new project structure

* Fixing link typo after refactoring

* Setting up Kotlin environment. Converting test to Kotlin.

* Deploying via SAM successfully.

* Added Kotlin example.

* Removing unused Gradle build file.

* Adding SAM template so can be used as an existing project and Java target compatibility

* Adding SAM template so can be used as an existing project

* Updating guidance to use SAM for build and deploy

* Restructuring separate Java and Kotlin examples.

* Updating core examples readme to represent new structure for Java and Kotlin examples.

* Refactoring application code for efficiency, updating build to cover tests too and is more idiomatic and readme to be more descriptive

* Updating to fix trailing \n

* Updating guidance to be more specific for examples

* Adopting new mechanism for specifying jvm target.

* accommodating new project structure

* Fixing link typo after refactoring

* Flattening structure back to original to make merging easier for v2

* Adding build for Kotlin Gradle

* Adding build for Kotlin Gradle - Restructuring Java examples to v1 approach

* Correcting paths

* Adding SNAPSHOT support and local capability for Maven. Testing using Java 1.8

* Reviewed and updated against PR comments.

* Un-commenting examples

* Adding validation step for IaC SAM

* Adding Terraform for Java projects IaC validator and linter

* Adding additional projects for SAM validation and matrix approach

* Refactoring stream function to process input logging example with a Lambda Function URL instead of APIGW.

* Demonstrating Java streaming response

* Refactoring stream function to process input logging example to return

* Update CONTRIBUTING.md

* fix: get trace id from system property when env var is not set (#1503)

* fix: check if XRAY Trace ID is present in System property

* chore: remove erroneous extra char in tests

* fix #1500 (#1506)

* feat: Add support for POWERTOOLS_LOGGER_LOG_EVENT (#1510)

* chore: Addition of Warn Message If Invalid Annotation Key While Tracing #1511 (#1512)

* feat: ALC (#1514)

* handle AWS_LAMBDA_LOG configuration

* ALC documentation + code review

* update doc

* chore:Prep release 1.18.0 (#1515)

* chore:prep release 1.18.0

* update version

* update version in kotlin example

* maven local repo in gradle example

* update changelog

---------

Co-authored-by: scottgerring <scottgerring@users.noreply.github.com>

* chore: update version to next snapshot: 1-19.0-SNAPSHOT (#1516)

* update version to next snapshot: 1-19.0-SNAPSHOT

* update version to next snapshot: 1-19.0-SNAPSHOT

* update version to next snapshot: 1-19.0-SNAPSHOT

* building only for LTS

* Add some more margin to the test pause (#1518)

* test: e2e tests with java 21 (#1517)

* e2e tests with java 21

* Run Java21 tests using the Java17 compiler

* Run all of the E2E tests in parallel, not just the first 3

* Try again

* .

* Let's try again

* Add some comment on Java21 to the repo

* Add caveat about lambda runtimes

* Clean up wording a little

---------

Co-authored-by: Scott Gerring <gerrings@amazon.com>

* update doc for ALC (#1520)

* chore: Testing java21 aspectj pre-release (#1519)

* e2e tests with java 21

* use aspectj 1.9.21-SNAPSHOT

* Fix log4j2.xml missing in logging test for java21

* rollback double runtime

* remove comment

* keep aspectj 1.9.7 in parent for java8 compatibility

* use M1 instead of snapshot

* update documentation for aspectj

* update documentation for aspectj

---------

Co-authored-by: Jerome Van Der Linden <jeromevdl@gmail.com>

* chore: Remove build cruft

* Adding context for using RequestStreamHandler

* removing pr_lint

* Update examples/powertools-examples-core/sam/src/main/java/helloworld/AppStream.java

Clarify usage of RequestStreamHandler.

Co-authored-by: Alexey Soshin <alexey.soshin@gmail.com>

---------

Co-authored-by: Jason Harris <harrzjas@amazon.com>
Co-authored-by: Scott Gerring <scottgerring@users.noreply.github.com>
Co-authored-by: Jason Harris <harrzjas@amazon.co.uk>
Co-authored-by: Jérôme Van Der Linden <117538+jeromevdl@users.noreply.github.com>
Co-authored-by: Michele Ricciardi <mriccia@amazon.com>
Co-authored-by: Alexey Soshin <alexey.soshin@gmail.com>
Co-authored-by: jdoherty <jdoherty07@gmail.com>
Co-authored-by: Scott Gerring <gerrings@amazon.com>
Co-authored-by: Jerome Van Der Linden <jeromevdl@gmail.com>

examples/powertools-examples-core/sam/src/main/java/helloworld/AppStream.java

@@ -17,22 +17,43 @@
 import com.amazonaws.services.lambda.runtime.Context;
 import com.amazonaws.services.lambda.runtime.RequestStreamHandler;
 import com.fasterxml.jackson.databind.ObjectMapper;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.Map;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import software.amazon.lambda.powertools.logging.Logging;
 import software.amazon.lambda.powertools.metrics.Metrics;
 
+import java.io.InputStreamReader;
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+
 public class AppStream implements RequestStreamHandler {
     private static final ObjectMapper mapper = new ObjectMapper();
+    private final static Logger log = LogManager.getLogger(AppStream.class);
 
     @Override
     @Logging(logEvent = true)
     @Metrics(namespace = "ServerlessAirline", service = "payment", captureColdStart = true)
-    public void handleRequest(InputStream input, OutputStream output, Context context) throws IOException {
-        Map map = mapper.readValue(input, Map.class);
+    // RequestStreamHandler can be used instead of RequestHandler for cases when you'd like to deserialize request body or serialize response body yourself, instead of allowing that to happen automatically
+    // Note that you still need to return a proper JSON for API Gateway to handle 
+    // See Lambda Response format for examples: https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html
+    public void handleRequest(InputStream input, OutputStream output, Context context) {
+        try (BufferedReader reader = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8));
+             PrintWriter writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(output, StandardCharsets.UTF_8)))) {
 
-        System.out.println(map.size());
+            log.info("Received: " + mapper.writerWithDefaultPrettyPrinter().writeValueAsString(mapper.readTree(reader)));
+
+            writer.write("{\"body\": \"" + System.currentTimeMillis() + "\"} ");
+        } catch (IOException e) {
+            log.error("Something has gone wrong: ", e);
+        }
     }
 }
+