code: public <B extends BackendObject> Observable<Void> send(final Collection<B> objects){
          return getWebService().save(isLoggedIn(),objects)
                 .subscribeOn(config.subscribeOn()).observeOn(config.observeOn());
      }
docs: Function used to save objects on remote server.
  @param objects Collection of objects to be saved.
  @param <B> Object type that extends BackendObject.
  @return Observable, no entity returned.