code: func (w *Worker) ResolveImageConfig(ctx context.Context, ref string, opt gw.ResolveImageConfigOpt, sm *session.Manager) (digest.Digest, []byte, error) {
  	// ImageSource is typically source/containerimage
  	resolveImageConfig, ok := w.ImageSource.(resolveImageConfig)
  	if !ok {
  		return "", nil, errors.Errorf("worker %q does not implement ResolveImageConfig", w.ID())
  	}
  	return resolveImageConfig.ResolveImageConfig(ctx, ref, opt, sm)
  }
docs: // ResolveImageConfig returns image config for an image