the preview hstSite of this mount. If this mount is already a preview mount, the same is returned as Mount.getHstSite().
Returned value can be null if this mount does not point to a hst:site as mountpoint
the preview Channel of this mount. If this mount is already a preview mount, the same is returned as Mount.getChannel().
Returned value can be null if this mount does not have a channel. If there is no explicit preview
channel, then the preview is the same as the live, and this method will return same instance as for Mount.getChannel()