Can't modify domain name with gsub and regex

[moattarwork]

I'm using the latest version of logstash and I'm trying to scramble the domain and use name the pattern which I'm using is gsub => [ "username", "(domain\).{2}(.+).{3}$", "-" ]

and with username as domain\username I expect to see username as -------us---ame but it replaces the whole username with single - which it shows that something is wrong with regex.

Is anybody know how to solve this?

[guyboertje]

Closing. This is not a bug. Ask for help on our discussion forum https://discuss.elastic.co/c/logstash