lnrpc: remove deprecated payment path

Not applicable anymore on the payment level with multi-part sends.

lnrpc/routerrpc/router_backend.go

@@ -1112,12 +1112,6 @@ func (r *RouterBackend) MarshallPayment(payment *channeldb.MPPayment) (
 		}
 	}
 
-	// Encode the hops from the successful route, if any.
-	path := make([]string, len(route.Hops))
-	for i, hop := range route.Hops {
-		path[i] = hex.EncodeToString(hop.PubKeyBytes[:])
-	}
-
 	msatValue := int64(payment.Info.Value)
 	satValue := int64(payment.Info.Value.ToSatoshis())
 
@@ -1153,7 +1147,6 @@ func (r *RouterBackend) MarshallPayment(payment *channeldb.MPPayment) (
 		ValueSat:        satValue,
 		CreationDate:    payment.Info.CreationTime.Unix(),
 		CreationTimeNs:  creationTimeNS,
-		Path:            path,
 		Fee:             int64(route.TotalFees().ToSatoshis()),
 		FeeSat:          int64(route.TotalFees().ToSatoshis()),
 		FeeMsat:         int64(route.TotalFees()),

lnrpc/rpc.proto

@@ -3097,8 +3097,7 @@ message Payment {
     /// Deprecated, use creation_time_ns
     int64 creation_date = 3 [deprecated = true];
 
-    /// The path this payment took.
+    reserved 4;
-    repeated string path = 4 [deprecated = true];
 
     /// Deprecated, use fee_sat or fee_msat.
     int64 fee = 5 [deprecated = true];

lnrpc/rpc.swagger.json

@@ -3936,13 +3936,6 @@
           "format": "int64",
           "title": "/ Deprecated, use creation_time_ns"
         },
-        "path": {
-          "type": "array",
-          "items": {
-            "type": "string"
-          },
-          "description": "/ The path this payment took."
-        },
         "fee": {
           "type": "string",
           "format": "int64",

lntest/itest/lnd_test.go

@@ -4336,15 +4336,12 @@ func testListPayments(net *lntest.NetworkHarness, t *harnessTest) {
 			len(paymentsResp.Payments), 1)
 	}
 	p := paymentsResp.Payments[0]
+	path := p.Htlcs[len(p.Htlcs)-1].Route.Hops
 
 	// Ensure that the stored path shows a direct payment to Bob with no
 	// other nodes in-between.
-	expectedPath := []string{
+	if len(path) != 1 || path[0].PubKey != net.Bob.PubKeyStr {
-		net.Bob.PubKeyStr,
+		t.Fatalf("incorrect path")
-	}
-	if !reflect.DeepEqual(p.Path, expectedPath) {
-		t.Fatalf("incorrect path, got %v, want %v",
-			p.Path, expectedPath)
 	}
 
 	// The payment amount should also match our previous payment directly.
@@ -14317,8 +14314,8 @@ func testHoldInvoicePersistence(net *lntest.NetworkHarness, t *harnessTest) {
 
 			// We wait for the payment attempt to have been
 			// properly recorded in the DB.
-			if len(payment.Path) == 0 {
+			if len(payment.Htlcs) == 0 {
-				return fmt.Errorf("path is empty")
+				return fmt.Errorf("no attempt recorded")
 			}
 
 			delete(payHashes, payment.PaymentHash)