Preconditions

Java 8
Intellij IDEA
Lombok (plugin + config)
./gradlew build (Linux), gradlew.bat build (Windows)

Lombok

File -> Settings -> Plugins
Browse repositories -> Lombok Plugin -> Install
Restart
File -> Settings
Build, execution, deployment -> Compiler -> Annotation Processors
Enable annotation processing

Running

Navigate to class DropboxApp (Ctrl + N).
Right click on class name and "Run".
Visit http://localhost:8080/.