@Test
  public void testConstrainedKeys() throws Exception {
    CacheCreation cache = new CacheCreation();
    RegionAttributesCreation attrs = new RegionAttributesCreation(cache);
    attrs.setKeyConstraint(String.class);
    cache.createRegion("root", attrs);

    testXml(cache);
  }
Tests creating a cache whose keys are constrained
geode-core/src/distributedTest/java/org/apache/geode/cache30/CacheXml66DUnitTest.java