lnrpc: add IsAmp to Invoice

lnrpc/invoicesrpc/invoices.swagger.json

@@ -463,6 +463,11 @@
           "type": "string",
           "format": "byte",
           "description": "The payment address of this invoice. This value will be used in MPP\npayments, and also for newer invoies that always require the MPP paylaod\nfor added end-to-end security."
+        },
+        "is_amp": {
+          "type": "boolean",
+          "format": "boolean",
+          "description": "Signals whether or not this is an AMP invoice."
         }
       }
     },

lnrpc/invoicesrpc/utils.go

@@ -147,6 +147,8 @@ func CreateRPCInvoice(invoice *channeldb.Invoice,
 		rpcHtlcs = append(rpcHtlcs, &rpcHtlc)
 	}
 
+	isAmp := invoice.Terms.Features.HasFeature(lnwire.AMPOptional)
+
 	rpcInvoice := &lnrpc.Invoice{
 		Memo:            string(invoice.Memo),
 		RHash:           rHash,
@@ -170,8 +172,9 @@ func CreateRPCInvoice(invoice *channeldb.Invoice,
 		State:           state,
 		Htlcs:           rpcHtlcs,
 		Features:        CreateRPCFeatures(invoice.Terms.Features),
-		IsKeysend:       len(invoice.PaymentRequest) == 0,
+		IsKeysend:       len(invoice.PaymentRequest) == 0 && !isAmp,
 		PaymentAddr:     invoice.Terms.PaymentAddr[:],
+		IsAmp:           isAmp,
 	}
 
 	if preimage != nil {

lnrpc/rpc.proto

@@ -3003,6 +3003,11 @@ message Invoice {
     for added end-to-end security.
     */
     bytes payment_addr = 26;
+
+    /*
+    Signals whether or not this is an AMP invoice.
+    */
+    bool is_amp = 27;
 }
 
 enum InvoiceHTLCState {

lnrpc/rpc.swagger.json

@@ -4387,6 +4387,11 @@
           "type": "string",
           "format": "byte",
           "description": "The payment address of this invoice. This value will be used in MPP\npayments, and also for newer invoies that always require the MPP paylaod\nfor added end-to-end security."
+        },
+        "is_amp": {
+          "type": "boolean",
+          "format": "boolean",
+          "description": "Signals whether or not this is an AMP invoice."
         }
       }
     },

rpcserver.go

@@ -4824,6 +4824,7 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		CltvExpiry:      invoice.CltvExpiry,
 		Private:         invoice.Private,
 		RouteHints:      routeHints,
+		Amp:             invoice.IsAmp,
 	}
 
 	if invoice.RPreimage != nil {