code: public Observable<Page<P2SVpnGatewayInner>> listByResourceGroupNextAsync(final String nextPageLink) {
          return listByResourceGroupNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<P2SVpnGatewayInner>>, Page<P2SVpnGatewayInner>>() {
                  @Override
                  public Page<P2SVpnGatewayInner> call(ServiceResponse<Page<P2SVpnGatewayInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Lists all the P2SVpnGateways in a resource group.
  
  @param nextPageLink The NextLink from the previous successful call to List operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;P2SVpnGatewayInner&gt; object