Understanding Auth-Worker Logging

[dovecot at ptld.com]

Sometimes when auth-worker gets logged there is an extra 'field' combined with the username and IP inside the sql() section.


dovecot[911]: auth-worker(8131): conn unix:auth-worker (pid=3870,uid=97): auth-worker<2>: sql(user at example.com,xxx.xxx.xxx.xxx,<8Q4ycCznAPdoiAwp>): Password mismatch (SHA1 of given password: 6ef33886cc5e17a60590cb4badac98d2960b6914)


What is the "<8Q4ycCznAPdoiAwp>" and why is it logged only sometimes?
Is there any documentation explaining what's inside of logs for dovecot?