code: public Observable<Page<SubnetInner>> listAsync(final String resourceGroupName, final String virtualNetworkName) {
          return listWithServiceResponseAsync(resourceGroupName, virtualNetworkName)
              .map(new Func1<ServiceResponse<Page<SubnetInner>>, Page<SubnetInner>>() {
                  @Override
                  public Page<SubnetInner> call(ServiceResponse<Page<SubnetInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Gets all subnets in a virtual network.
  
  @param resourceGroupName The name of the resource group.
  @param virtualNetworkName The name of the virtual network.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;SubnetInner&gt; object