Spring boot,Spring Securityを使用したform認証とGoogle OAuth2認証を併用したい

私が無知の為、大変ご面倒おかけしますが、力を貸して下さい。

実現したいこと

SpringSecurityを使用して、同じログイン画面でform認証とGoogle OAuth2認証を併用したいです。

起こっている問題

Google OAuth2認証はログイン出来、画面遷移するが、form認証を行うと、以下のエラーメッセージが現れてログインが出来ない。

ErrorMessage
1java.lang.IllegalStateException: Current user principal is not of type [org.springframework.security.oauth2.client.authentication.OAuth2AuthenticationToken]: UsernamePasswordAuthenticationToken [Principal=com.test.main.AuthUserDetails@62f854e2, Credentials=[PROTECTED], Authenticated=true, Details=WebAuthenticationDetails [RemoteIpAddress=0:0:0:0:0:0:0:1, SessionId=9793C4B6FBC9D3FA656F567410ED74E3], Granted Authorities=[USER]]
2	at org.springframework.web.servlet.mvc.method.annotation.ServletRequestMethodArgumentResolver.resolveArgument(ServletRequestMethodArgumentResolver.java:169) ~[spring-webmvc-5.3.13.jar:5.3.13]
3	at org.springframework.web.servlet.mvc.method.annotation.ServletRequestMethodArgumentResolver.resolveArgument(ServletRequestMethodArgumentResolver.java:124) ~[spring-webmvc-5.3.13.jar:5.3.13]
4	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-5.3.13.jar:5.3.13]
5

エラーが出ている該当のソースコード

Java:AuthUserDetails.java
1package com.test.main;
2
3import java.util.Collection;
4
5import org.springframework.security.core.GrantedAuthority;
6import org.springframework.security.core.userdetails.UserDetails;
7
8public class AuthUserDetails implements UserDetails {
9	
10	private AuthEntity auth;
11	private Collection<GrantedAuthority> authorities;
12	
13	public AuthUserDetails() {}
14	
15	public AuthUserDetails(AuthEntity auth, Collection<GrantedAuthority> authorities) {
16		this.auth = auth;
17		this.authorities = authorities;
18	}　←ここでエラー発生
19	
20	@Override
21	public Collection<? extends GrantedAuthority> getAuthorities() {
22		return this.authorities;
23	}
24
25	@Override
26	public String getPassword() {
27		return auth.getPassword();
28	}
29
30	@Override
31	public String getUsername() {
32		return auth.getUsername();
33	}
34
35	@Override
36	public boolean isAccountNonExpired() {
37		return true;
38	}
39
40	@Override
41	public boolean isAccountNonLocked() {
42		return true;
43	}
44
45	@Override
46	public boolean isCredentialsNonExpired() {
47		return true;
48	}
49
50	@Override
51	public boolean isEnabled() {
52		return true;
53	}
54}

関係があると思っているソースコード

HTML:login.html
1略
2<body>
3	<div>
4		<div>
5			<form action="#" th:action="@{/login}" method="post" th:object="${loginForm}" id="loginF">
6				<input type="text" id="username" name="username" placeholder="メールアドレス" /> 
7               <input type="password" id="password" name="password" placeholder="パスワード" />
8				<button type = "submit">
9			</form>
10			<div>
11				<a th:href="@{/oauth2/authorization/google}" class="anchor"><span>Googleアカウントでログイン</span></a>
12			</div>	
13		</div>
14	</div>
15</body>
16</html>

Java:DbSecurityConfig.java
1package com.test.main;
2
3import org.springframework.beans.factory.annotation.Autowired;
4import org.springframework.context.annotation.Bean;
5import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
6import org.springframework.security.config.annotation.web.builders.HttpSecurity;
7import org.springframework.security.config.annotation.web.builders.WebSecurity;
8import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
9import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
10import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
11import org.springframework.security.crypto.password.PasswordEncoder;
12import org.springframework.security.web.firewall.DefaultHttpFirewall;
13
14import com.komesuku.main.model.service.AuthAccountService;
15
16@EnableWebSecurity
17public class DbSecurityConfig extends WebSecurityConfigurerAdapter {
18
19	@Autowired
20	private AuthAccountService userDetailsService;
21	
22    @Bean
23    public PasswordEncoder passwordEncoder() {
24        return new BCryptPasswordEncoder();
25    }
26
27    @Override
28	public void configure(WebSecurity web) {
29        DefaultHttpFirewall firewall = new DefaultHttpFirewall();
30        web.httpFirewall(firewall);
31    }
32    
33    @Override
34    protected void configure(HttpSecurity http) throws Exception {
35    	http.authorizeRequests().antMatchers("/css/**", "/png/**", "/js/**", "/regist", "/forgot", "/message", "/registPass", "/registPassDone", "/reYesterday").permitAll()
36    			.anyRequest().authenticated()
37    			.and()
38    			.formLogin()
39    			.loginPage("/login").permitAll()
40    			.defaultSuccessUrl("/success",true)
41    			.and()
42    			.oauth2Login()
43    			.loginPage("/login").permitAll()
44    			.defaultSuccessUrl("/success",true)
45    			.and()
46    			.logout().logoutUrl("/logout").logoutSuccessUrl("/login").permitAll();
47    	http.requiresChannel().anyRequest().requiresSecure();
48    }
49    
50    @Override
51    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
52    	auth.userDetailsService(userDetailsService).passwordEncoder(passwordEncoder());
53    }
54}
55

Java:AuthAccountService.java
1package com.test.main.model.service;
2
3import org.springframework.beans.factory.annotation.Autowired;
4import org.springframework.jdbc.core.JdbcTemplate;
5import org.springframework.security.core.authority.AuthorityUtils;
6import org.springframework.security.core.userdetails.UserDetails;
7import org.springframework.security.core.userdetails.UserDetailsService;
8import org.springframework.security.core.userdetails.UsernameNotFoundException;
9import org.springframework.stereotype.Service;
10import org.springframework.transaction.annotation.Transactional;
11import org.springframework.util.ObjectUtils;
12
13import com.komesuku.main.AuthEntity;
14import com.komesuku.main.AuthMapper;
15import com.komesuku.main.AuthUserDetails;
16
17@Service
18public class AuthAccountService implements UserDetailsService {
19
20	@Autowired
21	private AuthMapper mapper;
22	
23	@Autowired
24    JdbcTemplate jdbcTemplate;
25	
26	@Override
27	public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
28		if(ObjectUtils.isEmpty(username)) {
29			throw new UsernameNotFoundException("ユーザー名を入力してください");
30		}
31		AuthEntity auth = mapper.findByUsername(username);
32		if(auth == null) {
33			throw new UsernameNotFoundException("ユーザーが見つかりません");
34		}
35		
36		return new AuthUserDetails(auth, AuthorityUtils.createAuthorityList("USER"));
37		
38	}
39}
40

Java:AuthEntity.java
1package com.test.main;
2
3import javax.validation.constraints.NotBlank;
4import javax.validation.constraints.Size;
5
6import lombok.Data;
7
8@Data
9public class AuthEntity {
10	
11	public AuthEntity(String username, String password) {
12		this.username = username;
13		this.password = password;
14	}
15	
16	@NotBlank(message="必須項目です")
17	@Size(max=50,message="必須項目です")
18	private String username;
19	
20	@NotBlank(message="必須項目です")
21	@Size(max=100,message="必須項目です")
22	private String password;
23
24}
25