Maestro Android SDK
· Maestro is a server-driven platform-agnostic library that allows to drive tests for both iOS and Android using the same implementation through an intuitive API.
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 maestro-sdk-android-1.27.0.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.