instance method expand_directories_into

# File lib/importmap/map.rb, line 137
    def expand_directories_into(paths)
      @directories.values.each do |mapping|
        if (absolute_path = absolute_root_of(mapping.dir)).exist?
          find_javascript_files_in_tree(absolute_path).each do |filename|
            module_filename = filename.relative_path_from(absolute_path)
            module_name     = module_name_from(module_filename, mapping)
            module_path     = module_path_from(module_filename, mapping)

            paths[module_name] = MappedFile.new(name: module_name, path: module_path, preload: mapping.preload)
          end
        end
      end
    end