code: public static void AssertLegalCosFilePath(String cosFilePath) throws ParamException {
          if (cosFilePath == null || !cosFilePath.startsWith("/") || cosFilePath.endsWith("/")) {
              throw new ParamException(
                      cosFilePath + " is not cos file path! Tips: make sure not ends with /");
          }
          AssertNotContainIllegalLetter(cosFilePath);
      }
docs: 判断用户指定的cos文件路径是否合法有效, 即不以/结尾
  
  @param cosFilePath cos文件路径
  @throws ParamException