samples: updated legacy field in detectintentaudio (#571)

Author: b-loved-dreamer

dialogflow/snippets/src/main/java/com/example/dialogflow/DetectIntentAudio.java

@@ -82,7 +82,11 @@ public static QueryResult detectIntentAudio(
       System.out.format(
           "Detected Intent: %s (confidence: %f)\n",
           queryResult.getIntent().getDisplayName(), queryResult.getIntentDetectionConfidence());
-      System.out.format("Fulfillment Text: '%s'\n", queryResult.getFulfillmentText());
+      System.out.format(
+          "Fulfillment Text: '%s'\n",
+          queryResult.getFulfillmentMessagesCount() > 0
+              ? queryResult.getFulfillmentMessages(0).getText()
+              : "Triggered Default Fallback Intent");
 
       return queryResult;
     }