I am writing this discussion to request adding this feature to Cisco Jabber.
i know this feature is not supported at the moment as per https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/jabber/Windows/12_6/jabw-b-release-notes-12-6.html
Space Characters in Credentials
The following rules apply to space characters and credentials:
Usernames can contain spaces in on-premises deployments.
Usernames cannot contain spaces in cloud-based deployments.
Passwords cannot contain spaces in any deployment scenario.
The first and last characters of usernames in on-premises deployments must not be spaces. This rule is also true for usernames synchronized from a directory source.