code: public Observable<Page<VpnConnectionInner>> listByVpnGatewayAsync(final String resourceGroupName, final String gatewayName) {
          return listByVpnGatewayWithServiceResponseAsync(resourceGroupName, gatewayName)
              .map(new Func1<ServiceResponse<Page<VpnConnectionInner>>, Page<VpnConnectionInner>>() {
                  @Override
                  public Page<VpnConnectionInner> call(ServiceResponse<Page<VpnConnectionInner>> response) {
                      return response.body();
                  }
              });
      }
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