Clone this repository using
git clone https://github.com/jlandure/appengine-java-quickstart
cd appengine-java-quickstart
Launch the devserver using the Docker image zenika/alpine-appengine-java
docker run --rm -it -h localhost -v ~/.m2:/root/.m2 -v $(pwd):/usr/src/app -w /usr/src/app -p 8080:8080 zenika/alpine-appengine-java
Open your browser to http://localhost:8080/hello and see something like
Hello App Engine - Standard using 1.9.58 Java 1.8
The code source is copied on purpose from https://github.com/GoogleCloudPlatform/getting-started-java/
See this specific folder to check the source code