WebSphere Application Server Heritage APIs
· Some of these APIs were created prior to specification standards and are not strategic in their use for creating portable applications. We encourage developers to create applications that are as portable as possible by using specification standards. So we only encourage the use of the heritage APIs for the migration of existing applications from traditional WebSphere to Liberty and we discourage the use of these APIs for new applications or maintaining existing applications.
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 heritageAPIs-1.0-23.0.0.8.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.