Fix review comments

Author: maswin

gateway-ha/src/main/java/io/trino/gateway/ha/router/BaseRoutingManager.java

@@ -28,6 +28,7 @@
 import jakarta.ws.rs.HttpMethod;
 
 import java.net.HttpURLConnection;
+import java.net.URI;
 import java.net.URL;
 import java.util.HashMap;
 import java.util.List;
@@ -208,7 +209,7 @@ private String searchAllBackendForQuery(String queryId)
                 Future<Integer> call =
                         executorService.submit(
                                 () -> {
-                                    URL url = new URL(target);
+                                    URL url = URI.create(target).toURL();
                                     HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                                     conn.setConnectTimeout((int) TimeUnit.SECONDS.toMillis(5));
                                     conn.setReadTimeout((int) TimeUnit.SECONDS.toMillis(5));
@@ -232,7 +233,10 @@ private String searchAllBackendForQuery(String queryId)
             log.warn("Query id [%s] not found", queryId);
         }
         // Fallback on first active backend if queryId mapping not found.
-        return gatewayBackendManager.getActiveBackends(defaultRoutingGroup).get(0).getProxyTo();
+        return gatewayBackendManager.getActiveBackends(defaultRoutingGroup).stream()
+                .findFirst()
+                .map(ProxyBackendConfiguration::getProxyTo)
+                .orElseThrow(() -> new IllegalStateException("No active backends available for default routing group: " + defaultRoutingGroup));
     }
 
     /**
@@ -255,7 +259,7 @@ private String findExternalUrlForUnknownQueryId(String queryId)
         return externalUrl;
     }
 
-    private static LoadingCache<String, String> buildCache(Function<String, String> loader)
+    private LoadingCache<String, String> buildCache(Function<String, String> loader)
     {
         return CacheBuilder.newBuilder()
                 .maximumSize(10000)

gateway-ha/src/main/java/io/trino/gateway/ha/router/QueryCountBasedRouter.java

@@ -231,7 +231,9 @@ public synchronized void updateClusterStats(List<ClusterStats> stats)
     @Override
     protected synchronized Optional<ProxyBackendConfiguration> selectBackend(List<ProxyBackendConfiguration> backends, String user)
     {
-        Optional<ProxyBackendConfiguration> cluster = backends.stream().min((a, b) -> compareStats(clusterStats.get(a.getName()), clusterStats.get(b.getName()), user));
+        Optional<ProxyBackendConfiguration> cluster = backends.stream()
+                .filter(backend -> clusterStats.containsKey(backend.getName()))
+                .min((a, b) -> compareStats(clusterStats.get(a.getName()), clusterStats.get(b.getName()), user));
         cluster.ifPresent(c -> updateLocalStats(clusterStats.get(c.getName()), user));
         return cluster;
     }