code: private void recordMount(SlotReference slot) {
          if (mediaMounts.add(slot)) {
              deliverMountUpdate(slot, true);
          }
          if (!mediaDetails.containsKey(slot)) {
              try {
                  VirtualCdj.getInstance().sendMediaQuery(slot);
              } catch (Exception e) {
                  logger.warn("Problem trying to request media details for " + slot, e);
              }
          }
      }
docs: Records that there is media mounted in a particular media player slot, updating listeners if this is a change.
  Also send a query to the player requesting details about the media mounted in that slot, if we don't already
  have that information.
  
  @param slot the slot in which media is mounted