code: public VpnConnectionInner beginCreateOrUpdate(String resourceGroupName, String gatewayName, String connectionName, VpnConnectionInner vpnConnectionParameters) {
          return beginCreateOrUpdateWithServiceResponseAsync(resourceGroupName, gatewayName, connectionName, vpnConnectionParameters).toBlocking().single().body();
      }
docs: Creates a vpn connection to a scalable vpn gateway if it doesn't exist else updates the existing connection.
  
  @param resourceGroupName The resource group name of the VpnGateway.
  @param gatewayName The name of the gateway.
  @param connectionName The name of the connection.
  @param vpnConnectionParameters Parameters supplied to create or Update a VPN Connection.
  @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 VpnConnectionInner object if successful.