diff --git a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportInferenceAction.java b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportInferenceAction.java
index 5ddb9b27dc4d3..0c12b5bb0fba6 100644
--- a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportInferenceAction.java
+++ b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportInferenceAction.java
@@ -12,7 +12,6 @@
 import org.elasticsearch.action.support.ActionFilters;
 import org.elasticsearch.inference.InferenceService;
 import org.elasticsearch.inference.InferenceServiceRegistry;
-import org.elasticsearch.inference.InferenceServiceResults;
 import org.elasticsearch.inference.Model;
 import org.elasticsearch.inference.UnparsedModel;
 import org.elasticsearch.injection.guice.Inject;
diff --git a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/external/request/openai/OpenAiUnifiedChatCompletionRequestEntity.java b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/external/request/openai/OpenAiUnifiedChatCompletionRequestEntity.java
index 50339bf851f7d..5b7b274f2351b 100644
--- a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/external/request/openai/OpenAiUnifiedChatCompletionRequestEntity.java
+++ b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/external/request/openai/OpenAiUnifiedChatCompletionRequestEntity.java
@@ -66,18 +66,21 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
             for (UnifiedCompletionRequest.Message message : unifiedRequest.messages()) {
                 builder.startObject();
                 {
-                    switch (message.content()) {
-                        case UnifiedCompletionRequest.ContentString contentString -> builder.field(CONTENT_FIELD, contentString.content());
-                        case UnifiedCompletionRequest.ContentObjects contentObjects -> {
-                            builder.startArray(CONTENT_FIELD);
-                            for (UnifiedCompletionRequest.ContentObject contentObject : contentObjects.contentObjects()) {
-                                builder.startObject();
-                                builder.field(TEXT_FIELD, contentObject.text());
-                                builder.field(TYPE_FIELD, contentObject.type());
-                                builder.endObject();
-                            }
-                            builder.endArray();
+                    if (message.content() instanceof UnifiedCompletionRequest.ContentString contentString) {
+                        builder.field(CONTENT_FIELD, contentString.content());
+                    } else if (message.content() instanceof UnifiedCompletionRequest.ContentObjects contentObjects) {
+                        builder.startArray(CONTENT_FIELD);
+                        for (UnifiedCompletionRequest.ContentObject contentObject : contentObjects.contentObjects()) {
+                            builder.startObject();
+                            builder.field(TEXT_FIELD, contentObject.text());
+                            builder.field(TYPE_FIELD, contentObject.type());
+                            builder.endObject();
                         }
+                        builder.endArray();
+                    } else {
+                        throw new IllegalArgumentException(
+                            Strings.format("Unsupported message.content class received: %s", message.content().getClass().getSimpleName())
+                        );
                     }
 
                     builder.field(ROLE_FIELD, message.role());