nit fixes

core/src/main/scala/kafka/server/ControllerApis.scala

@@ -1060,8 +1060,8 @@ class ControllerApis(
     // Nearly all RPCs should check MetadataVersion inside the QuorumController. However, this
     // RPC is consulting a cache which lives outside the QC. So we check MetadataVersion here.
     if (!apiVersionManager.features.metadataVersion().map(_.isControllerRegistrationSupported).orElse(false)) {
-      throw new UnsupportedVersionException("Direct-to-controller communication is not " +
-        "supported with the current MetadataVersion.")
+      throw new UnsupportedVersionException("There is no finalized MetadataVersion, so " +
+        "direct-to-controller communication is not supported.")
     }
     // Unlike on the broker, DESCRIBE_CLUSTER on the controller requires a high level of
     // permissions (ALTER on CLUSTER).

metadata/src/main/java/org/apache/kafka/metadata/publisher/FeaturesPublisher.java

@@ -27,15 +27,13 @@
 
 import org.slf4j.Logger;
 
-import java.util.Map;
 import java.util.Optional;
 
 
 public class FeaturesPublisher implements MetadataPublisher {
     private final Logger log;
     private final FaultHandler faultHandler;
-    private volatile FinalizedFeatures finalizedFeatures = new FinalizedFeatures(
-        Optional.empty(), Map.of(), -1);
+    private volatile FinalizedFeatures finalizedFeatures = FinalizedFeatures.UNKNOWN_FINALIZED_FEATURES;
 
     public FeaturesPublisher(
         LogContext logContext,

server-common/src/main/java/org/apache/kafka/server/common/FinalizedFeatures.java

@@ -26,6 +26,9 @@ public record FinalizedFeatures(
     Map<String, Short> finalizedFeatures,
     long finalizedFeaturesEpoch
 ) {
+    public static final FinalizedFeatures UNKNOWN_FINALIZED_FEATURES =
+        new FinalizedFeatures(Optional.empty(), Map.of(), -1);
+
     public static FinalizedFeatures fromKRaftVersion(MetadataVersion version) {
         return new FinalizedFeatures(Optional.of(version), Map.of(), -1);
     }