void addRootRegion(RegionCreation root) throws RegionExistsException {
    String name = root.getName();
    RegionCreation existing = (RegionCreation) roots.get(name);

    if (existing != null) {
      throw new RegionExistsException(existing);
    }

    roots.put(root.getName(), root);
  }
Sets the attributes of the root region

@throws RegionExistsException If this cache already contains a region with the same name as
        {@code root}.
geode-core/src/main/java/org/apache/geode/internal/cache/xmlcache/CacheCreation.java