This project is no longer maintained :(
Please user coordinates
com.github.sparkmuse : vaadin-archetype-springboot-application : 1.0.2
See: https://github.com/sparkmuse/vaadin-archetype-springboot-application
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window vaadin-archetype-springboot-application-1.0.3.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.