plugin-test-util
· Collection of utilities and classes used for testing JetBrains API plugins using flexmark-java spec files to provide input and expected results.
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 plugin-test-util-1.213.10.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.