cast_file_system_resolvers

# File actionview/lib/action_view/path_registry.rb, line 22
    def self.cast_file_system_resolvers(paths)
      paths = Array(paths)

      @file_system_resolver_mutex.synchronize do
        built_resolver = false
        paths = paths.map do |path|
          case path
          when String, Pathname
            path = File.expand_path(path)
            @file_system_resolvers[path] ||=
              begin
                built_resolver = true
                FileSystemResolver.new(path)
              end
          else
            path
          end
        end

        file_system_resolver_hooks.each(&:call) if built_resolver
      end

      paths
    end