code: public Observable<Page<NetworkWatcherInner>> listByResourceGroupAsync(String resourceGroupName) {
          return listByResourceGroupWithServiceResponseAsync(resourceGroupName).map(new Func1<ServiceResponse<List<NetworkWatcherInner>>, Page<NetworkWatcherInner>>() {
              @Override
              public Page<NetworkWatcherInner> call(ServiceResponse<List<NetworkWatcherInner>> response) {
                  PageImpl1<NetworkWatcherInner> page = new PageImpl1<>();
                  page.setItems(response.body());
                  return page;
              }
          });
      }
docs: Gets all network watchers by resource group.
  
  @param resourceGroupName The name of the resource group.
  @return the observable to the List&lt;NetworkWatcherInner&gt; object