Merge pull request #492 from marklogic/feature/more-polaris

Yet one more medium Polaris fix

Author: rjrudin

marklogic-spark-api/src/main/java/com/marklogic/spark/core/classifier/TextClassifierFactory.java

@@ -32,6 +32,7 @@ public static TextClassifier newTextClassifier(Context context) {
 
         if (context.hasOption(MOCK_CLASSIFIER_OPTION)) {
             String mockResponse = context.getStringOption(MOCK_CLASSIFIER_OPTION);
+            Objects.requireNonNull(mockResponse);
             semaphoreProxy = new MockSemaphoreProxy(mockResponse);
         } else if (host != null && !host.trim().isEmpty()) {
             try {