Register named writeables from UnifiedCompletionRequest

Author: Max Hniebergall

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceNamedWriteablesProvider.java

@@ -16,6 +16,7 @@
 import org.elasticsearch.inference.SecretSettings;
 import org.elasticsearch.inference.ServiceSettings;
 import org.elasticsearch.inference.TaskSettings;
+import org.elasticsearch.inference.UnifiedCompletionRequest;
 import org.elasticsearch.xpack.core.inference.results.ChatCompletionResults;
 import org.elasticsearch.xpack.core.inference.results.ErrorChunkedInferenceResults;
 import org.elasticsearch.xpack.core.inference.results.InferenceChunkedSparseEmbeddingResults;
@@ -137,11 +138,18 @@ public static List<NamedWriteableRegistry.Entry> getNamedWriteables() {
         addEisNamedWriteables(namedWriteables);
         addAlibabaCloudSearchNamedWriteables(namedWriteables);
 
+        addUnifiedNamedWriteables(namedWriteables);
+
         namedWriteables.addAll(StreamingTaskManager.namedWriteables());
 
         return namedWriteables;
     }
 
+    private static void addUnifiedNamedWriteables(List<NamedWriteableRegistry.Entry> namedWriteables) {
+        var writeables = UnifiedCompletionRequest.getNamedWriteables();
+        namedWriteables.addAll(writeables);
+    }
+
     private static void addAmazonBedrockNamedWriteables(List<NamedWriteableRegistry.Entry> namedWriteables) {
         namedWriteables.add(
             new NamedWriteableRegistry.Entry(