@Override
 public OccurenceInfo goPreviousOccurence() {
   return myOccurenceNavigator != null ? myOccurenceNavigator.goPreviousOccurence() : null;
 }
 @Override
 public String getPreviousOccurenceActionName() {
   return myOccurenceNavigator != null
       ? myOccurenceNavigator.getPreviousOccurenceActionName()
       : "";
 }
 @Override
 public boolean hasPreviousOccurence() {
   return myOccurenceNavigator != null && myOccurenceNavigator.hasPreviousOccurence();
 }