code: public static String requireNotEmpty(final String str) throws NullPointerException, IllegalArgumentException {
  	if (str.length() == 0) {
  	    throw new IllegalArgumentException();
  	}
  	return str;
      }
docs: Ensures the String is not null or empty.
  
  @param str
  String to check.
  @return The string.
  @throws IllegalArgumentException
  If the string was null or empty.