general: add ExternalHtlc to SwapInfo and add comments

Author: bhandras

interface.go

@@ -260,15 +260,22 @@ type SwapInfoKit struct {
 type SwapInfo struct {
 	loopdb.SwapStateData
 
+	loopdb.SwapContract
+
+	// LastUpdateTime is the time of the last state change.
 	LastUpdate time.Time
 
+	// SwapHash stores the swap preimage hash.
 	SwapHash lntypes.Hash
 
+	// SwapType describes whether this is a loop in or loop out swap.
 	SwapType swap.Type
 
-	loopdb.SwapContract
-
+	// HtlcAddress holds the HTLC address of the swap.
 	HtlcAddress btcutil.Address
+
+	// ExternalHtlc is set to true for external loop-in swaps.
+	ExternalHtlc bool
 }
 
 // LastUpdate returns the last update time of the swap

loopin.go

@@ -244,6 +244,7 @@ func (s *loopInSwap) sendUpdate(ctx context.Context) error {
 	s.log.Infof("Loop in swap state: %v", info.State)
 
 	info.HtlcAddress = s.htlc.Address
+	info.ExternalHtlc = s.ExternalHtlc
 
 	select {
 	case s.statusChan <- *info: