code: def get_custom_container_files():
      
  
      def is_special_file(name):
          return name.startswith('.')
  
      res = []
  
      top = infer_config_base_dir()/'containers'
      for root, dirnames, files in os.walk(top):
          for name in filter(is_special_file, dirnames):
              dirnames.remove(name)
  
          res.extend(
              [
                  os.path.join(root, name) for name in files
                  if not is_special_file(name) and name.endswith('.json')
              ])
  
      return res
docs: Traverses environment.get_path('CONTAINERS_DIR') to retrieve
      all .json files