`Cache.urls()` would prevent in-flight entries from being written.


## Version 3.14.3

_2019-09-10_

 *  Fix: Don't lose HTTP/2 flow control bytes when incoming data races with a stream close. If this
    happened enough then eventually the connection would stall.

 *  Fix: Acknowledge and apply inbound HTTP/2 settings atomically. Previously we had a race where we

    assertEquals(getKey + suffix, map.get(getKey));
    assertEquals(refreshKey + suffix, map.get(refreshKey));
  }

  @SuppressWarnings("ThreadPriorityCheck") // doing our best to test for races
  public void testExpandDuringLoading() throws InterruptedException {
    int count = 3;
    AtomicInteger callCount = new AtomicInteger();
    // tells the computing thread when to start computing

   * listeners for future n may complete before some for future n-1.) However, it is possible, if
   * one input completes with result X and another later with result Y, for Y to come before X in
   * the output future list. (Such races are impossible to solve without global synchronization of
   * all future completions. And they should have little practical impact.)
   *

	{abcd, "", -1, []string{"a", "b", "c", "d"}},
	{commas, ",", -1, []string{"1", "2", "3", "4"}},
	{dots, "...", -1, []string{"1", ".2", ".3", ".4"}},
	{faces, "☹", -1, []string{"☺☻", ""}},
	{faces, "~", -1, []string{faces}},
	{faces, "", -1, []string{"☺", "☻", "☹"}},
	{"1 2 3 4", " ", 3, []string{"1", "2", "3 4"}},
	{"1 2", " ", 3, []string{"1", "2"}},
	{"123", "", 2, []string{"1", "23"}},