code: public Observable<ServiceResponse<Page<P2SVpnServerConfigurationInner>>> listByVirtualWanWithServiceResponseAsync(final String resourceGroupName, final String virtualWanName) {
          return listByVirtualWanSinglePageAsync(resourceGroupName, virtualWanName)
              .concatMap(new Func1<ServiceResponse<Page<P2SVpnServerConfigurationInner>>, Observable<ServiceResponse<Page<P2SVpnServerConfigurationInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<P2SVpnServerConfigurationInner>>> call(ServiceResponse<Page<P2SVpnServerConfigurationInner>> page) {
                      String nextPageLink = page.body().nextPageLink();
                      if (nextPageLink == null) {
                          return Observable.just(page);
                      }
                      return Observable.just(page).concatWith(listByVirtualWanNextWithServiceResponseAsync(nextPageLink));
                  }
              });
      }
docs: Retrieves all P2SVpnServerConfigurations for a particular VirtualWan.
  
  @param resourceGroupName The resource group name of the VirtualWan.
  @param virtualWanName The name of the VirtualWan.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;P2SVpnServerConfigurationInner&gt; object