title: Java comparator for multi-column sorting?
body: <p>Is there any Java open-source comparator for comparing beans by multiple fields for multi-column sorting? Each column can be sorted asceding or descending.</p>
  
  <p>For single-column sorting it can be achieved by using <code>org.apache.commons.beanutils.BeanComparator</code> together with <code>org.springframework.util.comparator.InvertibleComparator</code>. </p>
  
  <p>I'm aware that this functionality is quite trivial to write, but what's the benefit from reinventing the wheel, if it was already written and tested?</p>