The new API is a bit different, both conceptually and practically:  https://github.com/sbt/sbt-remote-control/tree/wip/model-view-server-api/remote-controller/src/main/scala/com/typesafe/sbtrc/api

This kind of request doesn't exist.  It's ok for us to do it like this for now, but the current RunRequest mechanism is not multi-project friendly.   In the future, all requests will have to be marked with which project you wish to run on.  Then there's questions about whether one Echo server could support multiple "run" projects, or if you need a different one for each project....