public List<String> getOptionalObjectAttributes() {
        if(optionalObjectAttributes != null) {
            return Collections.unmodifiableList(optionalObjectAttributes);
        }
        return null;
    }
Gets the optional object attribute parameter indicating that customer also need
some extra information about an object in the response like Restore Status.

@return The optional parameter indicating that customer also need
     some extra information about an object on the response

@see ListObjectsV2Request#setOptionalObjectAttributes(List)
@see ListObjectsV2Request#withOptionalObjectAttributes(List)
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/model/ListObjectsV2Request.java