code: public Observable<Page<InstanceFailoverGroupInner>> listByLocationAsync(final String resourceGroupName, final String locationName) {
          return listByLocationWithServiceResponseAsync(resourceGroupName, locationName)
              .map(new Func1<ServiceResponse<Page<InstanceFailoverGroupInner>>, Page<InstanceFailoverGroupInner>>() {
                  @Override
                  public Page<InstanceFailoverGroupInner> call(ServiceResponse<Page<InstanceFailoverGroupInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Lists the failover groups in a location.
  
  @param resourceGroupName The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
  @param locationName The name of the region where the resource is located.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;InstanceFailoverGroupInner&gt; object