code: func (n OpaqueNetwork) EthernetCardBackingInfo(ctx context.Context) (types.BaseVirtualDeviceBackingInfo, error) {
  	var net mo.OpaqueNetwork
  
  	if err := n.Properties(ctx, n.Reference(), []string{"summary"}, &net); err != nil {
  		return nil, err
  	}
  
  	summary, ok := net.Summary.(*types.OpaqueNetworkSummary)
  	if !ok {
  		return nil, fmt.Errorf("%s unsupported network type: %T", n, net.Summary)
  	}
  
  	backing := &types.VirtualEthernetCardOpaqueNetworkBackingInfo{
  		OpaqueNetworkId:   summary.OpaqueNetworkId,
  		OpaqueNetworkType: summary.OpaqueNetworkType,
  	}
  
  	return backing, nil
  }
docs: // EthernetCardBackingInfo returns the VirtualDeviceBackingInfo for this Network