code: public static synchronized BookmarkManager getBookmarkManager(XMPPConnection connection) {
          BookmarkManager manager = bookmarkManagerMap.get(connection);
          if (manager == null) {
              manager = new BookmarkManager(connection);
              bookmarkManagerMap.put(connection, manager);
          }
          return manager;
      }
docs: Returns the <i>BookmarkManager</i> for a connection, if it doesn't exist it is created.
  
  @param connection the connection for which the manager is desired.
  @return Returns the <i>BookmarkManager</i> for a connection, if it doesn't
  exist it is created.
  @throws IllegalArgumentException when the connection is null.