add additional public servers, restart immediately on another when public server connection fails

src/main/java/com/sparrowwallet/sparrow/AppServices.java

@@ -209,6 +209,12 @@ public class AppServices {
             onlineProperty.setValue(false);
             onlineProperty.addListener(onlineServicesListener);
 
+            if(Config.get().getServerType() == ServerType.PUBLIC_ELECTRUM_SERVER) {
+                List<String> otherServers = Arrays.stream(PublicElectrumServer.values()).map(PublicElectrumServer::getUrl).filter(url -> !url.equals(Config.get().getPublicElectrumServer())).collect(Collectors.toList());
+                Config.get().setPublicElectrumServer(otherServers.get(new Random().nextInt(otherServers.size())));
+                restartService(connectionService);
+            }
+
             log.debug("Connection failed", failEvent.getSource().getException());
             EventManager.get().post(new ConnectionFailedEvent(failEvent.getSource().getException()));
         });

src/main/java/com/sparrowwallet/sparrow/net/PublicElectrumServer.java

@@ -3,7 +3,9 @@ package com.sparrowwallet.sparrow.net;
 public enum PublicElectrumServer {
     BLOCKSTREAM_INFO("blockstream.info", "ssl://blockstream.info:700"),
     ELECTRUM_BLOCKSTREAM_INFO("electrum.blockstream.info", "ssl://electrum.blockstream.info:50002"),
-    LUKECHILDS_CO("bitcoin.lukechilds.co", "ssl://bitcoin.lukechilds.co:50002");
+    LUKECHILDS_CO("bitcoin.lukechilds.co", "ssl://bitcoin.lukechilds.co:50002"),
+    EMZY_DE("electrum.emzy.de", "ssl://electrum.emzy.de:50002"),
+    BITAROO_NET("electrum.bitaroo.net", "ssl://electrum.bitaroo.net:50002");
 
     PublicElectrumServer(String name, String url) {
         this.name = name;

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

@@ -215,6 +215,11 @@ public class TransactionsController extends WalletFormController implements Init
         walletHistoryStatus(new WalletHistoryStatusEvent(walletForm.getWallet(), false));
     }
 
+    @Subscribe
+    private void connectionFailed(ConnectionFailedEvent event) {
+        walletHistoryStatus(new WalletHistoryStatusEvent(walletForm.getWallet(), false));
+    }
+
     @Subscribe
     public void walletUtxoStatusChanged(WalletUtxoStatusChangedEvent event) {
         if(event.getWallet().equals(getWalletForm().getWallet())) {

src/main/resources/com/sparrowwallet/sparrow/preferences/server.fxml

@@ -77,6 +77,8 @@
                             <PublicElectrumServer fx:constant="BLOCKSTREAM_INFO" />
                             <PublicElectrumServer fx:constant="ELECTRUM_BLOCKSTREAM_INFO" />
                             <PublicElectrumServer fx:constant="LUKECHILDS_CO" />
+                            <PublicElectrumServer fx:constant="EMZY_DE" />
+                            <PublicElectrumServer fx:constant="BITAROO_NET" />
                         </FXCollections>
                     </items>
                 </ComboBox>