@Test
  public void testHashIndexSetAddWithNullKey() throws Exception {
    int numEntries = 100;
    setupHashIndexSet(numEntries);

    assertEquals(numEntries, his.size());
    his.add(null, new Portfolio(numEntries + 1));
    assertEquals(numEntries + 1, his.size());
  }
we are "indexed" on indexKey. Equality of portfolios is based on ID indexKeys are based on 0 ->
numEntries IDs are startID -> startID + numEntries

@param numToCreate how many portfolios to create
@param startID the ID value to start incrementing from
geode-core/src/test/java/org/apache/geode/cache/query/internal/index/HashIndexSetJUnitTest.java