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 spring-cloud-starter-huawei-service-engine-config-1.11.0-2022.0.x.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.