@Override
  public void throwCacheExistsException() {
    throw new CacheExistsException(this, String.format("%s: An open cache already exists.", this),
        creationStack);
  }
This is for debugging cache-open issues such as {@link CacheExistsException}.
geode-core/src/main/java/org/apache/geode/internal/cache/GemFireCacheImpl.java