Thank you, everybody, for the review. I've merged the change, so the build is Gradle-based now. I hope I did not break too many workflows with that change.
Just in case, the new build steps are on the website ( https://calcite.apache.org/docs/howto.html#running-tests ). $ ./gradlew assemble # build the artifacts $ ./gradlew build -x test # build the artifacts, verify code style, skip tests $ ./gradlew check # verify code style, execute tests $ ./gradlew test # execute tests $ ./gradlew style # update code formatting (for auto-correctable cases) and verify style $ ./gradlew spotlessCheck checkstyleAll # report code style violations IDEs might remember that "the project was Maven-based", so the easiest way to migrate might be to remove project files and import Gradle build. Vladimir