Fix HintsDescriptor to translate messaging version to hints version

src/java/org/apache/cassandra/hints/HintsDescriptor.java

@@ -152,7 +152,40 @@ final class HintsDescriptor
      */
     static int currentStorageVersion()
     {
-        return StorageCompatibilityMode.current().storageMessagingVersion();
+        return hintsVersionFromMessagingVersion(StorageCompatibilityMode.current().storageMessagingVersion());
+    }
+
+    /**
+     * Translates a messaging version to the corresponding hints file version.
+     * This is necessary because hints versions have their own numbering scheme
+     * (1, 2, 3 for OSS versions 3.0, 4.0, 5.0) that differs from messaging versions.
+     *
+     * @param messagingVersion the messaging protocol version
+     * @return the hints file version corresponding to the messaging version
+     */
+    @VisibleForTesting
+    static int hintsVersionFromMessagingVersion(int messagingVersion)
+    {
+        switch (messagingVersion)
+        {
+            case MessagingService.VERSION_30:
+            case MessagingService.VERSION_3014:
+                return VERSION_30;
+            case MessagingService.VERSION_40:
+                return VERSION_40;
+            case MessagingService.VERSION_50:
+                return VERSION_50;
+            case MessagingService.VERSION_DS_10:
+                return VERSION_DS_10;
+            case MessagingService.VERSION_DS_11:
+                return VERSION_DS_11;
+            case MessagingService.VERSION_DS_12:
+                return VERSION_DS_12;
+            case MessagingService.VERSION_DS_20:
+                return VERSION_DS_20;
+            default:
+                throw new IllegalStateException("Unknown messaging version " + messagingVersion);
+        }
     }
 
     @SuppressWarnings("unchecked")

test/unit/org/apache/cassandra/hints/HintsDescriptorTest.java

@@ -248,4 +248,46 @@ public void testCurrentStorageVersionCC4ReturnsVersion40()
         assertEquals("CC_4 mode should produce VERSION_40 hints for rollback compatibility",
                      MessagingService.VERSION_40, version);
     }
+
+    @Test
+    public void testHintsVersionFromMessagingVersion()
+    {
+        // Test that all supported messaging versions can be translated to valid hints versions
+        int[] messagingVersions = {
+            MessagingService.VERSION_30,
+            MessagingService.VERSION_3014,
+            MessagingService.VERSION_40,
+            MessagingService.VERSION_50,
+            MessagingService.VERSION_DS_10,
+            MessagingService.VERSION_DS_11,
+            MessagingService.VERSION_DS_12,
+            MessagingService.VERSION_DS_20
+        };
+
+        for (int msgVersion : messagingVersions)
+        {
+            int hintsVersion = HintsDescriptor.hintsVersionFromMessagingVersion(msgVersion);
+            // Verify the translated version is valid by calling messagingVersion() on it
+            // This will throw if the hints version is not recognized
+            int roundTripped = HintsDescriptor.messagingVersion(hintsVersion);
+            assertThat(roundTripped).as("Messaging version for hints version derived from " + msgVersion)
+                                    .isGreaterThan(0);
+        }
+    }
+
+    @Test
+    public void testHintsVersionFromMessagingVersionCC4Compatibility()
+    {
+        int messagingVersion = StorageCompatibilityMode.CC_4.storageMessagingVersion();
+        assertEquals("CC_4 should return VERSION_40 messaging version", MessagingService.VERSION_40, messagingVersion);
+
+        int hintsVersion = HintsDescriptor.hintsVersionFromMessagingVersion(messagingVersion);
+        assertEquals("VERSION_40 messaging version should translate to hints VERSION_40",
+                     HintsDescriptor.VERSION_40, hintsVersion);
+
+        // Verify the hints version can be used without throwing AssertionError
+        int resolvedMsgVersion = HintsDescriptor.messagingVersion(hintsVersion);
+        assertEquals("Hints VERSION_40 should resolve back to messaging VERSION_40",
+                     MessagingService.Version.VERSION_40.value, resolvedMsgVersion);
+    }
 }