public static void registerKey1() {
    try {
      Region r = cache.getRegion(SEPARATOR + REGION_NAME);
      assertNotNull(r);
      r.registerInterest(k1, InterestResultPolicy.KEYS);
    } catch (Exception ex) {
      org.apache.geode.test.dunit.Assert.fail("failed while region.registerInterest()", ex);
    }
  }
put on non interest list ep and verify updates
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/InterestListEndpointDUnitTest.java