title: AtomicInteger: keep non-negative
body: <p>Is there a way to perform a "decrement if result is positive or zero" operation with an <code>AtomicInteger</code>?
  To clarify the desired behavior:</p>
  
  <ul>
  <li>if the current value is greater than zero, decrement</li>
  <li>if the current value is equal to zero, do nothing</li>
  <li>(negative current value is not handled)</li>
  </ul>