code: func (t *Transactor) CreateTransactionHeader(opts ...fab.TxnHeaderOpt) (fab.TransactionHeader, error) {
  
  	ctx, ok := contextImpl.RequestClientContext(t.reqCtx)
  	if !ok {
  		return nil, errors.New("failed get client context from reqContext for txn Header")
  	}
  
  	txh, err := txn.NewHeader(ctx, t.ChannelID, opts...)
  	if err != nil {
  		return nil, errors.WithMessage(err, "new transaction ID failed")
  	}
  
  	return txh, nil
  }
docs: // CreateTransactionHeader creates a Transaction Header based on the current context.