code: private static String getCidUriValue(String uri) {
  		int colon = uri.indexOf(':');
  		if (colon == 3) {
  			String scheme = uri.substring(0, colon);
  			return "cid".equalsIgnoreCase(scheme) ? uri.substring(colon + 1) : null;
  		}
  
  		if (uri.length() > 0 && uri.charAt(0) == '<' && uri.charAt(uri.length() - 1) == '>') {
  			return uri.substring(1, uri.length() - 1);
  		}
  
  		return null;
  	}
docs: Gets the value of the given "cid" URI.
  @param uri the "cid" URI
  @return the URI value or null if the given string is not a "cid" URI