Remove or transform user names before authentication?

[Brian Mathis]

I am using IdP 3 to authenticate against an LDAP backend.  The LDAP
backend has a restriction on characters allowed in usernames, so I
would like to be able to transform or remove those characters before
submitting to LDAP.

Is there a feature that does this?  I've done some searching buy
haven't found the right keywords yet.  Any examples that would help?

Thanks.