Modified to support "key content elements" which do not implements ContentElement.  THIS MODIFICATION CAUSE A SMALL BACKWARD INCOMPATIBILITY SINCE THE SIGNATURE OF THE handleServingFailure() METHOD SLIGHTLY CHANGED 
Modified to support "key content elements" which do not implements ContentElement. 
THIS MODIFICATION CAUSE A SMALL BACKWARD INCOMPATIBILITY SINCE THE SIGNATURE OF THE handleServingFailure() METHOD SLIGHTLY CHANGED 

ekiwi/jade-mirror,ekiwi/jade-mirror,ekiwi/jade-mirror,ekiwi/jade-mirror