public static Map<String, String> getJoystickButtonMappings(String joystickName) {
        Map<String, String> result = getButtonMappings(joystickName.trim(), false);
        if (result == null)
            return Collections.emptyMap();
        return Collections.unmodifiableMap(result);
    }
Returns a set of Joystick button name remappings if they exist otherwise
it returns an empty map.

@param joystickName which joystick (not null)
@return an unmodifiable map
jme3-core/src/main/java/com/jme3/input/JoystickCompatibilityMappings.java