code: public ClassFinder add(File file) {
      log.info("Adding file to look into: " + file.getAbsolutePath());
  
      if (fileCanContainClasses(file)) {
        String absPath = file.getAbsolutePath();
        if (placesToSearch.get(absPath) == null) {
          placesToSearch.put(absPath, file);
          for (AdditionalResourceLoader resourceLoader : resourceLoaders) {
            if (resourceLoader.canLoadAdditional(file)) resourceLoader.loadAdditional(file, this);
          }
        }
      } else {
        log.info("The given path '" + file.getAbsolutePath() + "' cannot contain classes!");
      }
  
      return this;
    }
docs: Add a jar file, zip file or directory to the list of places to search
  for classes.
  
  @param file the jar file, zip file or directory
  @return this