JSFTemplating is to work with Jakarta Faces technology to make building pages and components easier. It is used to define the layout of an example component.
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 jsftemplating-parent-4.0.3.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.