code: public Observable<Page<ContainerGroupInner>> listByResourceGroupAsync(final String resourceGroupName) {
          return listByResourceGroupWithServiceResponseAsync(resourceGroupName)
              .map(new Func1<ServiceResponse<Page<ContainerGroupInner>>, Page<ContainerGroupInner>>() {
                  @Override
                  public Page<ContainerGroupInner> call(ServiceResponse<Page<ContainerGroupInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Get a list of container groups in the specified subscription and resource group.
  Get a list of container groups in a specified subscription and resource group. This operation returns properties of each container group including containers, image registry credentials, restart policy, IP address type, OS type, state, and volumes.
  
  @param resourceGroupName The name of the resource group.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;ContainerGroupInner&gt; object