code: public static AnnotatorCache getInstance() {
        if (INSTANCE == null) {
           synchronized (AnnotatorCache.class) {
              if (INSTANCE == null) {
                 INSTANCE = new AnnotatorCache();
              }
           }
        }
        return INSTANCE;
     }
docs: Gets the instance of the cache.
  
  @return The instance of the <code>AnnotatorFactory</code>