only allow sending to paynyms where a notification transaction has previously been sent

src/main/java/com/sparrowwallet/sparrow/paynym/PayNymController.java

@@ -321,7 +321,9 @@ public class PayNymController {
 
     public boolean isLinked(PayNym payNym) {
         PaymentCode externalPaymentCode = payNym.paymentCode();
-        return getMasterWallet().getChildWallet(externalPaymentCode, payNym.segwit() ? ScriptType.P2WPKH : ScriptType.P2PKH) != null;
+        //As per BIP47 a notification transaction must have been sent from this wallet to enable the recipient to restore funds from seed
+        return getMasterWallet().getChildWallet(externalPaymentCode, payNym.segwit() ? ScriptType.P2WPKH : ScriptType.P2PKH) != null
+                && !getNotificationTransaction(externalPaymentCode).isEmpty();
     }
 
     public void updateFollowing() {
@@ -356,7 +358,7 @@ public class PayNymController {
         for(PayNym payNym : following) {
             if(!isLinked(payNym)) {
                 PaymentCode externalPaymentCode = payNym.paymentCode();
-                Map<BlockTransaction, WalletNode> unlinkedNotification = getMasterWallet().getNotificationTransaction(externalPaymentCode);
+                Map<BlockTransaction, WalletNode> unlinkedNotification = getNotificationTransaction(externalPaymentCode);
                 if(!unlinkedNotification.isEmpty() && !INVALID_PAYMENT_CODE_LABEL.equals(unlinkedNotification.keySet().iterator().next().getLabel())) {
                     unlinkedNotifications.putAll(unlinkedNotification);
                     unlinkedPayNyms.put(unlinkedNotification.keySet().iterator().next(), payNym);
@@ -607,6 +609,22 @@ public class PayNymController {
         return wallet.createWalletTransaction(utxoSelectors, utxoFilters, payments, opReturns, Collections.emptySet(), feeRate, minimumFeeRate, null, AppServices.getCurrentBlockHeight(), groupByAddress, includeMempoolOutputs, false);
     }
 
+    private Map<BlockTransaction, WalletNode> getNotificationTransaction(PaymentCode externalPaymentCode) {
+        Map<BlockTransaction, WalletNode> notificationTransaction = getMasterWallet().getNotificationTransaction(externalPaymentCode);
+        if(notificationTransaction.isEmpty()) {
+            for(Wallet childWallet : getMasterWallet().getChildWallets()) {
+                if(!childWallet.isNested()) {
+                    notificationTransaction = childWallet.getNotificationTransaction(externalPaymentCode);
+                    if(!notificationTransaction.isEmpty()) {
+                        return notificationTransaction;
+                    }
+                }
+            }
+        }
+
+        return notificationTransaction;
+    }
+
     public Wallet getMasterWallet() {
         Wallet wallet = AppServices.get().getWallet(walletId);
         return wallet.isMasterWallet() ? wallet : wallet.getMasterWallet();

src/main/java/com/sparrowwallet/sparrow/wallet/WalletController.java

@@ -90,7 +90,12 @@ public class WalletController extends WalletFormController implements Initializa
 
             try {
                 if(!existing) {
-                    FXMLLoader functionLoader = new FXMLLoader(AppServices.class.getResource("wallet/" + function.toString().toLowerCase() + ".fxml"));
+                    URL url = AppServices.class.getResource("wallet/" + function.toString().toLowerCase() + ".fxml");
+                    if(url == null) {
+                        throw new IllegalStateException("Cannot find wallet/" + function.toString().toLowerCase() + ".fxml");
+                    }
+
+                    FXMLLoader functionLoader = new FXMLLoader(url);
                     Node walletFunction = functionLoader.load();
                     walletFunction.setUserData(function);
                     WalletFormController controller = functionLoader.getController();