Is it possible to limit usernames length within range?

[ksevelyar]

This rule doesn't work:

 

username=[-=\\w\\[\\]\\{\\}\\(\\)\\@\\|\\.]{3,20}

 

Trying to connect as "ksevelyar" but fail:

 

Server connection rejected: Invalid username.

 

murmur: 1.2.3-8