@Test
  public void testRemoveAtWithNull() throws Exception {
    his = createHashIndexSet();
    assertTrue(his.isEmpty());
    assertFalse(his.removeAt(0));
  }
Test remove where we look for an instance that is not at the specified index slot
geode-core/src/test/java/org/apache/geode/cache/query/internal/index/HashIndexSetJUnitTest.java