correct logic

Author: ankit--sethi

libs/x-content/src/main/java/org/elasticsearch/xcontent/ObjectParser.java

@@ -334,7 +334,10 @@ private void throwExpectedStartObject(XContentParser parser, XContentParser.Toke
     private static void throwMissingRequiredFields(List<String[]> requiredFields) {
         final StringBuilder message = new StringBuilder();
         for (String[] fields : requiredFields) {
-            message.append("Required one of fields ").append(Arrays.toString(fields)).append(", but none were specified.");
+            message.append("Required one of fields ").append(Arrays.toString(fields)).append(", but none were specified. ");
+        }
+        if (message.isEmpty() == false) {
+            message.delete(message.length() - 1, message.length());
         }
         throw new IllegalArgumentException(message.toString());
     }