code: public static ClassScanner getInstance(ClassLoader classLoader) {
          ClassScanner scanner = classScannerMap.putIfAbsent(classLoader, new ClassScanner());
          if (scanner == null) {
              scanner = classScannerMap.get(classLoader);
              scanner.classLoader = classLoader;
          } else {
              LOGGER.info("当前ClassLoader [{}] 对应的ClassScanner已存在，直接返回当前已存在的并且忽略设置ClassLoader",
                  classLoader);
          }
  
          return scanner;
      }
docs: 使用指定ClassLoader获取一个ClassScanner实例
  
  @param classLoader 用于加载查找到的class的ClassLoader
  @return ClassScanner实例