Search for a User who is associated with this Driver Employee Number. Wildcard can be used by prepending/appending "%" to string. Example "%EmployeeNumber%". This property is negatable. If the first character of this search property is '!', then the API will know to negate the search logic. (e.g. field = "!EmployeeNumber%", is equivalent to: WHERE NOT LIKE 'EmployeeNumber%')