Add ProjectResolver to RemoteClusterService constructor

server/src/main/java/org/elasticsearch/node/NodeConstruction.java

@@ -1121,7 +1121,8 @@ public Map<String, String> queryFields() {
             settingsModule.getClusterSettings(),
             taskManager,
             telemetryProvider.getTracer(),
-            nodeEnvironment.nodeId()
+            nodeEnvironment.nodeId(),
+            projectResolver
         );
         final SearchResponseMetrics searchResponseMetrics = new SearchResponseMetrics(telemetryProvider.getMeterRegistry());
         final SearchTransportService searchTransportService = new SearchTransportService(

server/src/main/java/org/elasticsearch/node/NodeServiceProvider.java

@@ -42,6 +42,7 @@
 import org.elasticsearch.tasks.TaskManager;
 import org.elasticsearch.telemetry.tracing.Tracer;
 import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.transport.ClusterConnectionManager;
 import org.elasticsearch.transport.Transport;
 import org.elasticsearch.transport.TransportInterceptor;
 import org.elasticsearch.transport.TransportService;
@@ -119,9 +120,20 @@ TransportService newTransportService(
         ClusterSettings clusterSettings,
         TaskManager taskManager,
         Tracer tracer,
-        String nodeId
+        String nodeId,
+        ProjectResolver projectResolver
     ) {
-        return new TransportService(settings, transport, threadPool, interceptor, localNodeFactory, clusterSettings, taskManager);
+        return new TransportService(
+            settings,
+            transport,
+            threadPool,
+            interceptor,
+            localNodeFactory,
+            clusterSettings,
+            new ClusterConnectionManager(settings, transport, threadPool.getThreadContext()),
+            taskManager,
+            projectResolver
+        );
     }
 
     HttpServerTransport newHttpTransport(PluginsService pluginsService, NetworkModule networkModule) {

server/src/main/java/org/elasticsearch/transport/RemoteClusterService.java

@@ -24,7 +24,6 @@
 import org.elasticsearch.cluster.metadata.ProjectId;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.node.DiscoveryNodeRole;
-import org.elasticsearch.cluster.project.DefaultProjectResolver;
 import org.elasticsearch.cluster.project.ProjectResolver;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.ClusterSettings;
@@ -85,15 +84,14 @@ public boolean isRemoteClusterServerEnabled() {
     private final ProjectResolver projectResolver;
     private final boolean canUseSkipUnavailable;
 
-    @FixForMultiProject(description = "Inject the ProjectResolver instance.")
-    RemoteClusterService(Settings settings, TransportService transportService) {
+    RemoteClusterService(Settings settings, TransportService transportService, ProjectResolver projectResolver) {
         super(settings);
         this.isRemoteClusterClient = DiscoveryNode.isRemoteClusterClient(settings);
         this.isSearchNode = DiscoveryNode.hasRole(settings, DiscoveryNodeRole.SEARCH_ROLE);
         this.isStateless = DiscoveryNode.isStateless(settings);
         this.remoteClusterServerEnabled = REMOTE_CLUSTER_SERVER_ENABLED.get(settings);
         this.transportService = transportService;
-        this.projectResolver = DefaultProjectResolver.INSTANCE;
+        this.projectResolver = projectResolver;
         this.remoteClusters = projectResolver.supportsMultipleProjects()
             ? ConcurrentCollections.newConcurrentMap()
             : Map.of(ProjectId.DEFAULT, ConcurrentCollections.newConcurrentMap());
@@ -694,9 +692,9 @@ private Map<String, RemoteClusterConnection> getConnectionsMapForCurrentProject(
     /**
      * Returns the map of connections for the given {@link ProjectId}.
      */
+    @FixForMultiProject(description = "Assert ProjectId.DEFAULT should not be used in multi-project environment")
     private Map<String, RemoteClusterConnection> getConnectionsMapForProject(ProjectId projectId) {
         if (projectResolver.supportsMultipleProjects()) {
-            assert ProjectId.DEFAULT.equals(projectId) == false : "The default project ID should not be used in multi-project environment";
             return remoteClusters.computeIfAbsent(projectId, unused -> ConcurrentCollections.newConcurrentMap());
         }
         assert ProjectId.DEFAULT.equals(projectId) : "Only the default project ID should be used when multiple projects are not supported";

server/src/main/java/org/elasticsearch/transport/TransportService.java

@@ -18,6 +18,8 @@
 import org.elasticsearch.action.ActionListenerResponseHandler;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.cluster.project.DefaultProjectResolver;
+import org.elasticsearch.cluster.project.ProjectResolver;
 import org.elasticsearch.common.ReferenceDocs;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
@@ -232,7 +234,7 @@ public TransportService(
         );
     }
 
-    // NOTE: Only for use in tests
+    // Public access for tests.
     public TransportService(
         Settings settings,
         Transport transport,
@@ -249,12 +251,11 @@ public TransportService(
             transportInterceptor,
             localNodeFactory,
             clusterSettings,
-            new ClusterConnectionManager(settings, transport, threadPool.getThreadContext()),
             new TaskManager(settings, threadPool, taskHeaders)
         );
     }
 
-    @SuppressWarnings("this-escape")
+    // Public access for tests.
     public TransportService(
         Settings settings,
         Transport transport,
@@ -264,6 +265,31 @@ public TransportService(
         @Nullable ClusterSettings clusterSettings,
         ConnectionManager connectionManager,
         TaskManager taskManger
+    ) {
+        this(
+            settings,
+            transport,
+            threadPool,
+            transportInterceptor,
+            localNodeFactory,
+            clusterSettings,
+            connectionManager,
+            taskManger,
+            DefaultProjectResolver.INSTANCE
+        );
+    }
+
+    @SuppressWarnings("this-escape")
+    public TransportService(
+        Settings settings,
+        Transport transport,
+        ThreadPool threadPool,
+        TransportInterceptor transportInterceptor,
+        Function<BoundTransportAddress, DiscoveryNode> localNodeFactory,
+        @Nullable ClusterSettings clusterSettings,
+        ConnectionManager connectionManager,
+        TaskManager taskManger,
+        ProjectResolver projectResolver
     ) {
         this.transport = transport;
         transport.setSlowLogThreshold(TransportSettings.SLOW_OPERATION_THRESHOLD_SETTING.get(settings));
@@ -278,7 +304,7 @@ public TransportService(
         this.asyncSender = interceptor.interceptSender(this::sendRequestInternal);
         this.remoteClusterClient = DiscoveryNode.isRemoteClusterClient(settings);
         this.enableStackOverflowAvoidance = ENABLE_STACK_OVERFLOW_AVOIDANCE.get(settings);
-        remoteClusterService = new RemoteClusterService(settings, this);
+        remoteClusterService = new RemoteClusterService(settings, this, projectResolver);
         responseHandlers = transport.getResponseHandlers();
         if (clusterSettings != null) {
             clusterSettings.addSettingsUpdateConsumer(TransportSettings.TRACE_LOG_INCLUDE_SETTING, this::setTracerLogInclude);