Spec under camouflage

A 'text conditioner' applies two rules in order: (1) if the text is shorter than 3 characters (or null), return it unchanged; (2) otherwise return only its **middle two** characters (for even length, the two straddling the center; for odd length, the center character plus the one after it). Implement process(String s). Examples: "code" → "od", "abc" → "bc", "ab" → "ab", "x" → "x".