code: public static Node stripElementContentWhitespace(Node original) {
          Node cloned = original.cloneNode(true);
          cloned.normalize();
          stripECW(cloned);
          return cloned;
      }
docs: Creates a new Node (of the same type as the original node) that
  is similar to the orginal but doesn't contain any text or CDATA
  nodes that only consist of whitespace.
  
  <p>This doesn't have any effect if applied to a text or CDATA
  node itself.</p>
  
  @since XMLUnit 2.6.0