code: public Observable<Page<SpatialAnchorsAccountInner>> listByResourceGroupAsync(final String resourceGroupName) {
          return listByResourceGroupWithServiceResponseAsync(resourceGroupName)
              .map(new Func1<ServiceResponse<Page<SpatialAnchorsAccountInner>>, Page<SpatialAnchorsAccountInner>>() {
                  @Override
                  public Page<SpatialAnchorsAccountInner> call(ServiceResponse<Page<SpatialAnchorsAccountInner>> response) {
                      return response.body();
                  }
              });
      }
docs: List Resources by Resource Group.
  
  @param resourceGroupName Name of an Azure resource group.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;SpatialAnchorsAccountInner&gt; object