Replace deprecated bisq explorer settings

If user preferences were set to a bisq explorer that has been
retired, switch it to another explorer from the provided list.

Users can still choose their own explorer, or enter a custom
explorer address (such as their local node).

core/src/main/java/bisq/core/user/Preferences.java

@@ -309,15 +309,25 @@ private void setupPreferences() {
         useStandbyModeProperty.set(prefPayload.isUseStandbyMode());
         cssThemeProperty.set(prefPayload.getCssTheme());
 
+        // a list of previously-used federated explorers
+        // if user preference references any deprecated explorers we need to select a new valid explorer
+        String deprecatedExplorers = "(bsq.bisq.cc|bsq.vante.me|bsq.emzy.de|bsq.sqrrm.net|bsq.bisq.services|bsq.ninja).*";
+
         // if no valid Bitcoin block explorer is set, select the 1st valid Bitcoin block explorer
         ArrayList<BlockChainExplorer> btcExplorers = getBlockChainExplorers();
-        if (getBlockChainExplorer() == null || getBlockChainExplorer().name.length() == 0)
+        if (getBlockChainExplorer() == null ||
+                getBlockChainExplorer().name.length() == 0 ||
+                getBlockChainExplorer().name.matches(deprecatedExplorers)) {
             setBlockChainExplorer(btcExplorers.get(0));
+        }
 
         // if no valid BSQ block explorer is set, randomly select a valid BSQ block explorer
         ArrayList<BlockChainExplorer> bsqExplorers = getBsqBlockChainExplorers();
-        if (getBsqBlockChainExplorer() == null || getBsqBlockChainExplorer().name.length() == 0)
+        if (getBsqBlockChainExplorer() == null ||
+                getBsqBlockChainExplorer().name.length() == 0 ||
+                getBsqBlockChainExplorer().name.matches(deprecatedExplorers)) {
             setBsqBlockChainExplorer(bsqExplorers.get((new Random()).nextInt(bsqExplorers.size())));
+        }
 
         tradeCurrenciesAsObservable.addAll(prefPayload.getFiatCurrencies());
         tradeCurrenciesAsObservable.addAll(prefPayload.getCryptoCurrencies());