when key is null, skip running predict (opensearch-project#2402)

Author: mingshl

plugin/src/test/java/org/opensearch/ml/rest/RestMLInferenceIngestProcessorIT.java

@@ -115,6 +115,10 @@ public void testMLInferenceProcessorWithObjectFieldType() throws Exception {
         String index_name = "daily_index";
         createPipelineProcessor(createPipelineRequestBody, "diary_embedding_pipeline");
         createIndex(index_name, createIndexRequestBody);
+        // Skip test if key is null
+        if (OPENAI_KEY == null) {
+            return;
+        }
         uploadDocument(index_name, "1", uploadDocumentRequestBody);
         Map document = getDocument(index_name, "1");
         List embeddingList = JsonPath.parse(document).read("_source.diary_embedding");
@@ -197,6 +201,10 @@ public void testMLInferenceProcessorWithNestedFieldType() throws Exception {
         String index_name = "book_index";
         createPipelineProcessor(createPipelineRequestBody, "embedding_pipeline");
         createIndex(index_name, createIndexRequestBody);
+        // Skip test if key is null
+        if (OPENAI_KEY == null) {
+            return;
+        }
         uploadDocument(index_name, "1", uploadDocumentRequestBody);
         Map document = getDocument(index_name, "1");