No listen to ldap.authentication.before

[cesarluna]

Iam use DAP Authentication with the FOSUserBundle e but not working event ldap.authentication.before
`security:
hide_user_not_found: false
encoders:
FOS\UserBundle\Model\UserInterface: bcrypt

# https://symfony.com/doc/current/security.html#b-configuring-how-users-are-loaded
providers:
    fos_userbundle:
        id: fos_user.user_provider.username

in_memory:

memory: ~

firewalls:
    # disables authentication for assets and the profiler, adapt it according to your needs
    dev:
        pattern: ^/(_(profiler|wdt)|css|images|js)/
        security: false

    main:
        pattern: ^/
        form_login:
            provider: fos_userbundle
            csrf_token_generator: security.csrf.token_manager
            default_target_path: /admin

        logout:       true
        guard:
            authenticators:
                - ldap_tools.security.ldap_guard_authenticator
        anonymous:    true`