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 kerneos-flex-examples-examples-extensible-module-extensions-auto-insurance-client-2.2.1.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.