@Test
  public void testBug36590() throws Exception {
    QueryService qs;
    qs = CacheUtils.getQueryService();

    qs.createIndex("keyIndex", IndexType.FUNCTIONAL, "keys", SEPARATOR + "portfolios.keySet keys");
    Region rgn = CacheUtils.getRegion(SEPARATOR + "portfolios");
    rgn.put("4", new Portfolio(4));
    rgn.put("5", new Portfolio(5));
    Query qr = qs.newQuery(
        "Select distinct  * from " + SEPARATOR + "portfolios.keySet keys where keys = '4'");
    SelectResults sr = (SelectResults) qr.execute();
    assertEquals(sr.size(), 1);
  }
Creation of index on key path derived from Region.Entry object obtained via keySet , fails as
that function was not supported in the QRegion & DummyQRegion
geode-core/src/integrationTest/java/org/apache/geode/cache/query/functional/IndexCreationJUnitTest.java