code: private void checkRootDirectoryNotOverlap(String dir, Set<String> skinRootDirectories) {
  
  		String rootDir = removeLocaleSuffixIfExist(dir);
  		for (Iterator<String> itSkinDir = skinRootDirectories.iterator(); itSkinDir.hasNext();) {
  			String skinDir = PathNormalizer.asDirPath(itSkinDir.next());
  			if (!skinDir.equals(dir)) {
  				skinDir = removeLocaleSuffixIfExist(skinDir);
  				if (skinDir.startsWith(rootDir)) {
  					throw new BundlingProcessException(
  							"There is a misconfiguration. It is not allowed to have a skin root directory containing another one.");
  				}
  			}
  		}
  	}
docs: Check if there are no directory which is contained in another root
  directory,
  
  @param dir
  the root directory to check
  @param skinRootDirectories
  the root directories