_AMQ_User = null, when connection is authenticated via TextFileCertificateLoginModule

Cause: The _AMQ_User property on the notification message generated when a new consumer is created on the broker is null when the broker is configured to authenticate users via their SSL certificate because there is no actual username submitted when creating the consumer since the SSL certificate is used for authentication. Consequence: Potentially important audit information is not provided in the CONSUMER_CREATED notification message. Fix: Include the validated username as well as SSL certificate information in the notification message. Result: All relevant audit information should be present in the notification message.