docs: @Pure
  	public static String toFirstUpper(String s) {
  		if (s == null || s.length() == 0)
  			return s;
  		if (Character.isUpperCase(s.charAt(0)))
  			return s;
  		if (s.length() == 1)
  			return s.toUpperCase();
  		return s.substring(0, 1).toUpperCase() + s.substring(1);
  	}