How to fix Hibernate LazyInitializationException: failed to lazily initialize a collection of roles, could not initialize proxy – no Session

You need to either add fetch=FetchType.EAGER inside your ManyToMany annotations to automatically pull back child entities:

@ManyToMany(fetch = FetchType.EAGER)

A better option would be to implement a spring transactionManager by adding the following to your spring configuration file:

<bean id="transactionManager"
    class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory" />
</bean>

<tx:annotation-driven />

You can then add an @Transactional annotation to your authenticate method like so:

@Transactional
public Authentication authenticate(Authentication authentication)

This will then start a db transaction for the duration of the authenticate method allowing any lazy collection to be retrieved from the db as and when you try to use them.