code: public P2SVpnGatewayInner createOrUpdate(String resourceGroupName, String gatewayName, P2SVpnGatewayInner p2SVpnGatewayParameters) {
          return createOrUpdateWithServiceResponseAsync(resourceGroupName, gatewayName, p2SVpnGatewayParameters).toBlocking().last().body();
      }
docs: Creates a virtual wan p2s vpn gateway if it doesn't exist else updates the existing gateway.
  
  @param resourceGroupName The resource group name of the P2SVpnGateway.
  @param gatewayName The name of the gateway.
  @param p2SVpnGatewayParameters Parameters supplied to create or Update a virtual wan p2s vpn gateway.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws ErrorException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the P2SVpnGatewayInner object if successful.