private String getDefaultVersion(Set<String> keys, String appName) {
    SortedSet<String> listOfApps = new TreeSet<String>();
    for (String key : keys) {
      if (key.split(":")[0].contentEquals(appName)) {
        listOfApps.add(key);
      }
    }
    return listOfApps.size() > 0 ? listOfApps.last() : null;
  }
Returns the application under test in the format of "appName:appVersion", or "appName" if the supported application
does not have any version associated with it, or returns null if the requested app is not in the apps store. If the
launch activity is also specified with requested application then just return the requested application as app under
test so it can be later installed to the device by SelendroidStandaloneDriver.

@param supportedApps The list of supported apps in the apps store.
@return The application under test in "appName" or "appName:appVersion" format, or null if the application is not
        in the list of supported apps and the launch activity is not specified.
selendroid-common/src/main/java/io/selendroid/common/SelendroidCapabilities.java