Simple REST API for Raspberry Pi based on http://pi4j.com/. How to setup your Raspberry please read my tutorial https://tobias.blickle.online/controlling-raspberry-pi-ports-via-rest-api-provided-tomcat.
Store your portconfiguration in web.xml property online.blickle.pi.PortConfiguration as JSON string, deploy the WAR to Tomcat and your REST service is up and running!
Swagger API documentation can be found here: https://tobias.blickle.online/wp-content/uploads/piweb/doc/