TestSupport.assertThat(a.removeAll(nullList) == false,
"idempotent removeAll did not return false");
List yanl = newInstance(null);
yanl.addAll(nullList);
TestSupport.assertThat(yanl.removeAll(nullList) == true,
"mutating removeAll() did not return true");
TestSupport.assertThat(yanl.size() == 0,
"empty list had non-zero size");
TestSupport.assertThat(yanl.removeAll(newInstance(null)) == false,
"idempotent removeAll did not return false");