code: private static Document getUserDocument() throws Exception {
          if (userDoc == null || userFileParsed != userFile.lastModified() || userFileBytesLoaded != userFile.length()) {
              synchronized(XmlUsersFileModule.class) {
                  if (userDoc == null || userFileParsed != userFile.lastModified() || userFileBytesLoaded != userFile.length()) {
                      userDoc = DataUtils.getDocumentFromFile(userFile);
                      userFileParsed = userFile.lastModified();
                      userFileBytesLoaded = userFile.length();
                  }
              }
          }
          return userDoc;
      }
docs: Quick and dirty caching.
  @return DOM of a parsed user file
  @throws Exception