Lambada Framework lets you to build serverless REST API's with JAVA. It implements the JAX-RS API and
deploys your application easily to AWS Lambda and API Gateway
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window lambada-0.0.6.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
