@Override
      public void hook(int spot) throws RuntimeException {
        switch (spot) {
          case 6: // processAction in IndexManager
            hooked = true;
            // wait until some thread unhooks.
            while (hooked) {
              Wait.pause(20);
            }
            break;
          default:
            break;
        }
      }
This tests if index updates are blocked while region.clear() is called and indexes are being
reinitialized.
geode-core/src/distributedTest/java/org/apache/geode/cache/query/internal/index/ConcurrentIndexInitOnOverflowRegionDUnitTest.java