code: public static boolean isNullOrWhitespaceOnly(String str) {
  		if (str == null || str.length() == 0) {
  			return true;
  		}
  
  		final int len = str.length();
  		for (int i = 0; i < len; i++) {
  			if (!Character.isWhitespace(str.charAt(i))) {
  				return false;
  			}
  		}
  		return true;
  	}
docs: Checks if the string is null, empty, or contains only whitespace characters.
  A whitespace character is defined via {@link Character#isWhitespace(char)}.
  
  @param str The string to check
  @return True, if the string is null or blank, false otherwise.