Fix for result preview exception for hierarchical facets.
Fix for result preview exception for hierarchical facets.

marks/Keshif,geoapi/Keshif,cchapati/Keshif,IntegralExplorer/Keshif,marks/Keshif,IntegralExplorer/Keshif,geoapi/Keshif,geoapi/Keshif,IntegralExplorer/Keshif,marks/Keshif,NeilBryant/Keshif,cchapati/Keshif,NeilBryant/Keshif,NeilBryant/Keshif,adilyalcin/Keshif,cchapati/Keshif