Multiple login features

I would like to give the client the possibility to choose to login to my application either using google, facebook or my own implemented user data.

What I have so far is, I created my own CustomUserDetailsService class, which is working fine. I'm looking up the database and check if user exist and the password is equal. Now, I would like to extend the authentication to be able to use for example the google openId.

I was thinking of creating a new CustomUserDetailsServiceGoogle which implements UserDetailsService, but of course it failse because it expects only one implemantation of UserDetailsService.

My app-security.xml looks like this:

HTML Code:

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

    <http use-expressions="true" auto-config="true">
            <intercept-url pattern="/account/**" access="hasRole('ROLE_USER')" />
               
                <form-login login-page="/auth/login"
                                        authentication-failure-url="/auth/denied"
                                        default-target-url="/account/profile" />

                <access-denied-handler error-page="/auth/denied" />

                <logout invalidate-session="true"
                                logout-success-url="/"
                                logout-url="/logout"
                                delete-cookies="JSESSIONID" />
                               
        <remember-me />
       
        <session-management invalid-session-url="/" />       
       
    </http>
   
   
   
        <beans:bean id="passwordEncoder" class="org.springframework.security.authentication.encoding.Md5PasswordEncoder" />
        <beans:bean id="customUserDetailsService" class="com.app.security.CustomUserDetailsService" />

        <authentication-manager>
                <authentication-provider user-service-ref="customUserDetailsService">
                        <password-encoder ref="passwordEncoder"/>
                </authentication-provider>
        </authentication-manager>
       

</beans:beans>

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Does anyone have a link to an example of supporting 2 or many authentication features?