code: func NewGRPCProvisionerServerShim(p terraform.ResourceProvisioner) *GRPCProvisionerServer {
  	sp, ok := p.(*schema.Provisioner)
  	if !ok {
  		return nil
  	}
  	return &GRPCProvisionerServer{
  		provisioner: sp,
  	}
  }
docs: // NewGRPCProvisionerServerShim wraps a terraform.ResourceProvisioner in a
  // proto.ProvisionerServer implementation. If the provided provisioner is not a
  // *schema.Provisioner, this will return nil,