code: public void updateFromResource(CmsResource resource) {
  
          // first set the last modification date
          updateDateLastModified(resource.getDateLastModified());
          // now use both release and expiration date from the resource to update the expires info
          updateDateExpires(resource.getDateReleased());
          updateDateExpires(resource.getDateExpired());
      }
docs: Updates the "last modified" date for this context as well as the
  "expires" date with the values from a given resource.<p>
  
  The "expires" date is the calculated from the given date values
  of resource release and expiration and also the current time.<p>
  
  @param resource the resource to use for updating the context values