fix unique ID message for inference ID matches trained model ID

Author: Max Hniebergall

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/messages/Messages.java

@@ -281,6 +281,8 @@ public final class Messages {
     public static final String FIELD_CANNOT_BE_NULL = "Field [{0}] cannot be null";
     public static final String MODEL_ID_MATCHES_EXISTING_MODEL_IDS_BUT_MUST_NOT =
         "Model IDs must be unique. Requested model ID [{}] matches existing model IDs but must not.";
+    public static final String INFERENCE_ID_MATCHES_EXISTING_MODEL_IDS_BUT_MUST_NOT =
+        "Inference endpoint IDs must be unique. Requested inference endpoint ID [{}] matches existing trained model ID(s) but must not.";
     public static final String MODEL_ID_DOES_NOT_MATCH_EXISTING_MODEL_IDS_BUT_MUST_FOR_IN_CLUSTER_SERVICE =
         "Requested model ID [{}] does not have a matching trained model and thus cannot be updated.";
     public static final String INFERENCE_ENTITY_NON_EXISTANT_NO_UPDATE = "The inference endpoint [{}] does not exist and cannot be updated";

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

@@ -153,7 +153,7 @@ protected void masterOperation(
         if ((assignments == null || assignments.isEmpty()) == false) {
             listener.onFailure(
                 ExceptionsHelper.badRequestException(
-                    Messages.MODEL_ID_MATCHES_EXISTING_MODEL_IDS_BUT_MUST_NOT,
+                    Messages.INFERENCE_ID_MATCHES_EXISTING_MODEL_IDS_BUT_MUST_NOT,
                     request.getInferenceEntityId()
                 )
             );