private void createOrRetrieveRegion() {
    // Retrieve the local session region
    sessionRegion = cache.getRegion((String) properties.get(CacheProperty.REGION_NAME));

    // If necessary, create the regions on the server and client
    if (sessionRegion == null) {
      // Create the PR on the servers
      createSessionRegionOnServers();

      // Create the region on the client
      sessionRegion = createLocalSessionRegion();
      LOG.debug("Created session region: " + sessionRegion);
    } else {
      LOG.debug("Retrieved session region: " + sessionRegion);

      // Register interest in case users provide their own client cache region
      if (sessionRegion.getAttributes().getDataPolicy() != DataPolicy.EMPTY) {
        sessionRegion.registerInterestForAllKeys(InterestResultPolicy.KEYS);
      }
    }
  }
Set some default properties for this cache if they haven't already been set
extensions/geode-modules-session-internal/src/main/java/org/apache/geode/modules/session/internal/common/ClientServerSessionCache.java