chamilo-lms2/app/config/fos/fos_user.yml

fos_user:
    db_driver: orm # can be orm or odm
    firewall_name:  main

    # if you change the class configuration, please also alter the sonata_user.yml file
    user_class:     Chamilo\UserBundle\Entity\User

    group:
        group_class:   Chamilo\UserBundle\Entity\Group
        group_manager: sonata.user.orm.group_manager

    service:
        user_manager: sonata.user.orm.user_manager