code: @InterfaceAudience.Public
      public void close() {
          synchronized (lockDatabases) {
              Log.d(Database.TAG, "Closing " + this);
  
              // Close all database:
              // Snapshot of the current open database to avoid concurrent modification as
              // the database will be forgotten (removed from the databases map) when it is closed:
              Database[] openDbs = databases.values().toArray(new Database[databases.size()]);
              for (Database database : openDbs)
                  database.close();
              databases.clear();
  
              // Stop reachability:
              context.getNetworkReachabilityManager().stopListening();
  
              // Shutdown ScheduledExecutorService:
              if (workExecutor != null && !workExecutor.isShutdown())
                  Utils.shutdownAndAwaitTermination(workExecutor);
  
              Log.d(Database.TAG, "Closed " + this);
          }
      }
docs: Releases all resources used by the Manager instance and closes all its databases.