checkout-sdk-android
· 1D3 SDK for Android is a software development kit for fast integration of payment solutions right in your mobile application for 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 checkout-sdk-android-1.15.2.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.