./gradlew clean // cleanup all build directories
./gradlew build --parallel // build all PDF files
./gradlew <subproject>::clean // Cleanup build directory
./gradlew <subproject>::build // build PDF files for sub project
./gradlew <subproject>::open // open all PDF files for sub project
Required packages for generation of documentation
sudo apt-get install ruby-dev libxslt1-dev graphviz