channeldb: store hold invoice

lnrpc/invoicesrpc/utils.go

@@ -65,11 +65,10 @@ func CreateRPCInvoice(invoice *channeldb.Invoice,
 			invoice.Terms.State)
 	}
 
-	return &lnrpc.Invoice{
+	rpcInvoice := &lnrpc.Invoice{
 		Memo:            string(invoice.Memo[:]),
 		Receipt:         invoice.Receipt[:],
 		RHash:           decoded.PaymentHash[:],
-		RPreimage:       preimage[:],
 		Value:           int64(satAmt),
 		CreationDate:    invoice.CreationDate.Unix(),
 		SettleDate:      settleDate,
@@ -87,7 +86,13 @@ func CreateRPCInvoice(invoice *channeldb.Invoice,
 		AmtPaidMsat:     int64(invoice.AmtPaid),
 		AmtPaid:         int64(invoice.AmtPaid),
 		State:           state,
-	}, nil
+	}
+
+	if preimage != channeldb.UnknownPreimage {
+		rpcInvoice.RPreimage = preimage[:]
+	}
+
+	return rpcInvoice, nil
 }
 
 // CreateRPCRouteHints takes in the decoded form of an invoice's route hints