Erro em página login comJSF e Spring Security

Programação Java
#1

Boa tarde estou seguindo um tutorial de como fazer uma página de login com spring security e jsf, nom meu bean tenho o seguinte código:

private Usuario usuario;

    public UsuarioBean() {
                    usuario = new Usuario();
                    SecurityContext context = SecurityContextHolder.getContext();
                    if (context instanceof SecurityContext){
                        Authentication authentication = context.getAuthentication();
                        if (authentication instanceof Authentication){
                            usuario.setUsername(((User) authentication.getPrincipal()).getUsername()); //erro aqui.
                        }
                    }
        }

ao iniciar o projeto sempre ocorre esse erro: java.lang.String cannot be cast to org.springframework.security.core.userdetails.User
o que poderia ser?

Meu applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
    <b:beans xmlns="http://www.springframework.org/schema/security"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:b="http://www.springframework.org/schema/beans"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
                                http://www.springframework.org/schema/beans/spring-beans.xsd
                                http://www.springframework.org/schema/security
                                http://www.springframework.org/schema/security/spring-security-3.1.xsd">

        <http auto-config="true" use-expressions="true">
            <intercept-url pattern="/inicio/inicio.xhtml" access="hasRole('ROLE_USER')" />
            <form-login login-page="/login.xhtml" authentication-failure-url="/login.xhtml?erro=true" />
        </http>

        <authentication-manager>
            <authentication-provider>
                <jdbc-user-service data-source-ref="dataSource"
                    users-by-username-query="SELECT username, password, enable FROM usuario WHERE username=?"
                    authorities-by-username-query="SELECT Usuario_username as username, autorizacoes_nome as authority FROM usuario_autorizacao WHERE Usuario_username=?" />
            </authentication-provider>
        </authentication-manager>

        <b:bean id="dataSource"
            class="org.springframework.jdbc.datasource.DriverManagerDataSource">
            <b:property name="url" value="jdbc:mysql://localhost:3306/database" />
            <b:property name="driverClassName" value="com.mysql.jdbc.Driver" />
            <b:property name="username" value="root" />
            <b:property name="password" value="senha" />
        </b:bean>

    </b:beans>

Entidade Usuario:

 @Entity
    @Table(name = "USUARIO")
    public class Usuario implements Serializable {
        
        private static final long serialVersionUID = 1L;

        @Id
        private String username;
            
        private String password;
        
        @Column(name = "enable", columnDefinition = "BOOLEAN")
        private boolean enable;
        
        @OneToMany
        private List<Autorizacao> autorizacoes;

        //gets e sets

Entidade Autorizacao:

@Entity
    @Table(name = "AUTORIZACAO")
    public class Autorizacao implements Serializable{

        private static final long serialVersionUID = 1L;
        
        @Id
        private String nome;

//gets e sets