validate output

Signed-off-by: Sicheng Song <sicheng.song@outlook.com>

Author: b4sjoo

ml-algorithms/src/main/java/org/opensearch/ml/engine/algorithms/remote/RemoteConnectorExecutor.java

@@ -78,9 +78,10 @@ default ModelTensorOutput executePredict(MLInput mlInput) throws IOException {
         } else {
             validateInputSchema(mlInput);
             preparePayloadAndInvokeRemoteModel(mlInput, tensorOutputs);
-            validateOutputSchema(tensorOutputs);
         }
-        return new ModelTensorOutput(tensorOutputs);
+        ModelTensorOutput modelTensorOutput = new ModelTensorOutput(tensorOutputs);
+        validateOutputSchema(modelTensorOutput);
+        return modelTensorOutput;
     }
 
     default void setScriptService(ScriptService scriptService) {}
@@ -163,10 +164,10 @@ private void validateInputSchema(MLInput mlInput) throws IOException {
         }
     }
 
-    private void validateOutputSchema(List<ModelTensors> tensorOutput) throws IOException {
+    private void validateOutputSchema(ModelTensorOutput modelTensorOutput) throws IOException {
         if (getConnector().getModelInterface() != null && getConnector().getModelInterface().get("output") != null) {
             String schemaString = getConnector().getModelInterface().get("output");
-            ConnectorUtils.validateSchema(schemaString, tensorOutput.toString());
+            ConnectorUtils.validateSchema(schemaString, modelTensorOutput.toXContent(XContentFactory.jsonBuilder(), ToXContent.EMPTY_PARAMS).toString());
         }
     }
 }