code: func expandHostVirtualSwitchSpec(d *schema.ResourceData) *types.HostVirtualSwitchSpec {
  	obj := &types.HostVirtualSwitchSpec{
  		Mtu:      int32(d.Get("mtu").(int)),
  		NumPorts: int32(d.Get("number_of_ports").(int)),
  		Bridge:   expandHostVirtualSwitchBondBridge(d),
  		Policy:   expandHostNetworkPolicy(d),
  	}
  	// If there are no NICs, we need to nil-out Bridge, as a
  	// HostVirtualSwitchBondBridge with no NICs is an invalid config.
  	if len(obj.Bridge.(*types.HostVirtualSwitchBondBridge).NicDevice) < 1 {
  		obj.Bridge = nil
  	}
  	return obj
  }
docs: // expandHostVirtualSwitchSpec reads certain ResourceData keys and returns a
  // HostVirtualSwitchSpec.