code: public static synchronized HttpFileUploadManager getInstanceFor(XMPPConnection connection) {
          HttpFileUploadManager httpFileUploadManager = INSTANCES.get(connection);
  
          if (httpFileUploadManager == null) {
              httpFileUploadManager = new HttpFileUploadManager(connection);
              INSTANCES.put(connection, httpFileUploadManager);
          }
  
          return httpFileUploadManager;
      }
docs: Obtain the HttpFileUploadManager responsible for a connection.
  
  @param connection the connection object.
  @return a HttpFileUploadManager instance