public static By className(String className) {
    if (className == null)
      throw new IllegalArgumentException("Cannot find elements when className is null.");
    return new ByClass(className);
  }
@param id The value of the "id" attribute to search for
@return a By which locates elements by the value of the "id" attribute.
selendroid-server/src/main/java/io/selendroid/server/model/By.java