}
  }

  interface Backend {
    fun nanoTime(): Long

    fun coordinatorNotify(taskRunner: TaskRunner)

    fun coordinatorWait(
      taskRunner: TaskRunner,
      nanos: Long,
    )

    fun <T> decorate(queue: BlockingQueue<T>): BlockingQueue<T>

    fun execute(
      taskRunner: TaskRunner,
      runnable: Runnable,
    )
  }

  class RealBackend(

  directory: Path,
  maxSize: Long,
  fileSystem: FileSystem,
  taskRunner: TaskRunner,
) : Closeable,
  Flushable {
  /** Create a cache of at most [maxSize] bytes in [directory]. */
  constructor(
    fileSystem: FileSystem,
    directory: Path,
    maxSize: Long,
  ) : this(
    directory,
    maxSize,
    fileSystem,
    TaskRunner.INSTANCE,
  )

          "please call response.close()"
      }
      check(!requestBodyOpen)
    }

    if (newRoutePlanner) {
      val routePlanner =
        RealRoutePlanner(
          taskRunner = client.taskRunner,
          connectionPool = connectionPool,
          readTimeoutMillis = client.readTimeoutMillis,
          writeTimeoutMillis = client.writeTimeoutMillis,