The thread is a bit old but i think this could probably save someone's time ...
I ran into the same problem as the original question, that the type is showed as Symfony\Component\Security\Core\User\User
It eventually turned out that i was logged in using an in memory user
my security.yml looks something like this
security:
providers:
chain_provider:
chain:
providers: [in_memory, fos_userbundle]
fos_userbundle:
id: fos_user.user_manager
in_memory:
memory:
users:
user: { password: userpass, roles: [ 'ROLE_USER' ] }
admin: { password: adminpass, roles: [ 'ROLE_ADMIN', 'ROLE_SONATA_ADMIN' ] }
the in_memory user type is always Symfony\Component\Security\Core\User\User if you want to use your own entity, log in using that provider's user.
Thanks, hj