code: public Observable<ServiceResponse<Page<VpnConnectionInner>>> listByVpnGatewayWithServiceResponseAsync(final String resourceGroupName, final String gatewayName) {
          return listByVpnGatewaySinglePageAsync(resourceGroupName, gatewayName)
              .concatMap(new Func1<ServiceResponse<Page<VpnConnectionInner>>, Observable<ServiceResponse<Page<VpnConnectionInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<VpnConnectionInner>>> call(ServiceResponse<Page<VpnConnectionInner>> page) {
                      String nextPageLink = page.body().nextPageLink();
                      if (nextPageLink == null) {
                          return Observable.just(page);
                      }
                      return Observable.just(page).concatWith(listByVpnGatewayNextWithServiceResponseAsync(nextPageLink));
                  }
              });
      }
docs: Retrieves all vpn connections for a particular virtual wan vpn gateway.
  
  @param resourceGroupName The resource group name of the VpnGateway.
  @param gatewayName The name of the gateway.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;VpnConnectionInner&gt; object