code: protected String stripKnownPrefix(String str, String prefix)
     {
  
        int startIndex = str.lastIndexOf(prefix);
        if (startIndex != -1)
        {
           return str.substring(startIndex + prefix.length());
        }
  
        return null;
     }
docs: Strip everything up to and including a given prefix from a string.
  
  @param str The string to process
  @param prefix The prefix
  @return the stripped string or <code>null</code> if the prefix has not been found