code: public String renameApp(String appName, String newName) {
          return connection.execute(new AppRename(appName, newName), apiKey).getName();
      }
docs: Rename an existing app.
  @param appName Existing app name. See {@link #listApps()} for names that can be used.
  @param newName New name to give the existing app.
  @return the new name of the object