}
              });
      assertEquals("Counts not as expected", Ints.asList(deltas), actualCounts);
    } finally {
      pool.shutdownNow();
    }

    // Since we have access to the backing map, verify that there are no zeroes in the map
    for (AtomicInteger value : map.values()) {
      assertTrue("map should not contain a zero", value.get() != 0);
    }
  }

                }
              });
      assertEquals("Counts not as expected", Ints.asList(deltas), actualCounts);
    } finally {
      pool.shutdownNow();
    }

    // Since we have access to the backing map, verify that there are no zeroes in the map
    for (AtomicInteger value : map.values()) {
      assertTrue("map should not contain a zero", value.get() != 0);
    }
  }