Implementations of this class map between an SSO Username.
Which is typically the username as logged into the front-end application.
And the TOBOUsername, which is typically a secondary username
given to an entity within the OMS that may be traded on behalf of.
If TOBOUsers do not exist. A default implementation of this class
should simply reflect the name of the SSOUsername.
Returns the TOBO Username given an SSO Username.
A TOBOUsername is a secondary username associated with
an Entity that one may trade on behalf of.
If No Such Username exists, you may return the