(SpringSecurity)ログイン後にTOPページを表示できない

お世話になります。
Spring Boot で認証機能を実装してみる
上記サイトを参考にし、SpringBoot＋SpringSecurityでログイン認証を実装しようと思っています。
ログイン画面でID、PWを入力してログインボタンを押してもTOPページを表示することができません。

試したこと

わざと間違ったIDとPWを入力した場合は、?errorというURLに変わるので、ID、PW間違いは原因でないと思います。
.defaultSuccessUrlでログイン後のurlを指定してみても解決しませんでした。

以下にソースコードを記載致します。


//LoginController.java
package com.sample;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class LoginController
{
    public static final String PAGE = "/login";
    private static final String HTML = "login";

    @RequestMapping(value = LoginController.PAGE)
    public String top(Model model)
    {
        return LoginController.HTML;
    }
}

//TopController.java

package com.sample;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class TopController
{
    public static final String PAGE = "/";
    private static final String HTML = "top";

    @RequestMapping(value = TopController.PAGE, method = RequestMethod.GET)
    public String top(Model model)
    {
        return TopController.HTML;
    }
}

//WebSecurityConfig.java

package com.sample;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.core.userdetails.UserDetailsService;

@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter
{
    private UserDetailsService userDetailsService;

    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception
    {
        httpSecurity.authorizeRequests().anyRequest().authenticated();
        httpSecurity.formLogin().loginPage(LoginController.PAGE).usernameParameter("user")
                .passwordParameter("pass").permitAll();
    }

    @Override
    protected void configure(AuthenticationManagerBuilder authenticationManagerBuilder)
            throws Exception
    {
        authenticationManagerBuilder.userDetailsService(this.userDetailsService);
    }

    @Autowired
    public void setUserDetailsService(UserDetailsService userDetailsService)
    {
        this.userDetailsService = userDetailsService;
    }
}


//MemberEntity.java

package com.sample;

import java.util.Collection;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;

@Entity
@Table(name = "member")
public class MemberEntity implements UserDetails
{
    private static final long serialVersionUID = 1667698003975566301L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(nullable = false, unique = true)
    private String username;

    @Column(nullable = false)
    private String password;

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities()
    {
        return null;
    }

    @Override
    public String getPassword()
    {
        return this.password;
    }

    @Override
    public String getUsername()
    {
        return this.username;
    }

    @Override
    public boolean isAccountNonExpired()
    {
        return true;
    }

    @Override
    public boolean isAccountNonLocked()
    {
        return true;
    }

    @Override
    public boolean isCredentialsNonExpired()
    {
        return true;
    }

    @Override
    public boolean isEnabled()
    {
        return true;
    }
}

//MemberRepository.java

package com.sample;

import org.springframework.data.jpa.repository.JpaRepository;

import com.sample.MemberEntity;

public interface MemberRepository extends JpaRepository<MemberEntity, Long>
{
    public MemberEntity findByUsername(String username);
}


//MemberServiceImpl.java

package com.sample;

import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

import com.sample.MemberEntity;
import com.sample.MemberRepository;

@Service
public class MemberServiceImpl implements UserDetailsService
{
    private MemberRepository memberRepository;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException
    {
        if (StringUtils.isEmpty(username))
        {
            throw new UsernameNotFoundException("");
        }

        MemberEntity memberEntity = memberRepository.findByUsername(username);
        if (memberEntity == null)
        {
            throw new UsernameNotFoundException("");
        }

        return memberEntity;
    }

    @Autowired
    public void setMemberRepository(MemberRepository memberRepository)
    {
        this.memberRepository = memberRepository;
    }
}

以上となります。
何卒宜しくお願い致します。