An API gateway (preferable Spring/Playframwork) that proxies two different REST end points and outputs the results into a merged (also JSON) response. For example you could use these two endpoints: http://jsonplaceholder.typicode.com/users/1 to obtain a userResponse's data http://jsonplaceholder.typicode.com/posts?userId=1 to obtain all comments written by that userResponse

./gradlew clean build -i && java -jar build/libs/async-api-gateway-0.0.1-SNAPSHOT.jar

curl localhost:8080/gateway/users/1 | jq