@Override
  public DiskStore findDiskStore(String name) {
    if (name == null) {
      name = defaultDiskStoreName;
    }
    return diskStores.get(name);
  }
Used by unit tests to allow them to change the default disk store name.
geode-core/src/main/java/org/apache/geode/internal/cache/GemFireCacheImpl.java