code: private void deliverDatabaseUpdate(SlotReference slot, Database database, boolean available) {
          for (final DatabaseListener listener : getDatabaseListeners()) {
              try {
                  if (available) {
                      listener.databaseMounted(slot, database);
                  } else {
                      listener.databaseUnmounted(slot, database);
                  }
              } catch (Throwable t) {
                  logger.warn("Problem delivering rekordbox database availability update to listener", t);
              }
          }
      }
docs: Send a database announcement to all registered listeners.
  
  @param slot the media slot whose database availability has changed
  @param database the database whose relevance has changed
  @param available if {@code} true, the database is newly available, otherwise it is no longer relevant