FirebaseKMM
· FirebaseKMM is a Firebase Extension that supports cross-platform projects also based on Firebase Kotlin SDK, allowing you to directly from iOS and Android.
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 firebase-config-0.7.1.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.