Parent project that holds module projects for base classes for persistence like base entity or base business objects and mapper for mapping between them.
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 persistence-api-6.6.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
