@Override
  public InternalCache getExistingCache() {
    InternalCache result = cache;
    if (result == null) {
      throw new CacheClosedException(
          "A cache has not yet been created.");
    }
    result.getCancelCriterion().checkCancelInProgress(null);
    if (result.isClosed()) {
      throw result.getCacheClosedException(
          "The cache has been closed.", null);
    }
    return result;
  }
update the loner port with an integer that may be more unique than the default port (zero).
This updates the ID in place and establishes new default settings for the manufacture of new
IDs.

@param newPort the new port to use
geode-core/src/main/java/org/apache/geode/distributed/internal/LonerDistributionManager.java