xds: Squelch ADS reconnection error logs

Workaround for #8886, as we wait on a real fix. The regular load
balancing disconnections are confusing users and will train users to
start ignoring gRPC warnings. At present, it is better to have no log
than excessively log.

xds/src/main/java/io/grpc/xds/XdsNameResolver.java

@@ -129,6 +129,9 @@ final class XdsNameResolver extends NameResolver {
   private XdsClient xdsClient;
   private CallCounterProvider callCounterProvider;
   private ResolveState resolveState;
+  // Workaround for https://github.com/grpc/grpc-java/issues/8886 . This should be handled in
+  // XdsClient instead of here.
+  private boolean receivedConfig;
 
   XdsNameResolver(
       @Nullable String targetAuthority, String name, ServiceConfigParser serviceConfigParser,
@@ -293,6 +296,7 @@ private void updateResolutionResult() {
             .setServiceConfig(parsedServiceConfig)
             .build();
     listener.onResult(result);
+    receivedConfig = true;
   }
 
   @VisibleForTesting
@@ -715,7 +719,7 @@ public void onError(final Status error) {
       syncContext.execute(new Runnable() {
         @Override
         public void run() {
-          if (stopped) {
+          if (stopped || receivedConfig) {
             return;
           }
           listener.onError(error);
@@ -865,6 +869,7 @@ private void cleanUpRoutes() {
       }
       routingConfig = RoutingConfig.empty;
       listener.onResult(emptyResult);
+      receivedConfig = true;
     }
 
     private void cleanUpRouteDiscoveryState() {
@@ -912,7 +917,7 @@ public void onError(final Status error) {
         syncContext.execute(new Runnable() {
           @Override
           public void run() {
-            if (RouteDiscoveryState.this != routeDiscoveryState) {
+            if (RouteDiscoveryState.this != routeDiscoveryState || receivedConfig) {
               return;
             }
             listener.onError(error);