private int createServerCache() throws Exception {
    cacheRule.createCache();

    // no region is created on server

    CacheServer cacheServer = cacheRule.getCache().addCacheServer();
    cacheServer.setPort(0);
    cacheServer.start();
    return cacheServer.getPort();
  }
When server is running but region is not created on server. Client sends register interest
request, server checks for region, and if region is not exist on server, it throws an exception
to the client. Hence, client marks server as dead.

<p>
To avoid this, there should not be any check of region before registration. And region
registration should not fail due to non existent region.

<p>
TRAC #36805: Interest registration on server should not check for region in server's cache.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/RegisterInterestOnServerWithoutRegionRegressionTest.java