Fix documentation code block bug.

Closes gh-12980

Author: 1993heqiang

docs/modules/ROOT/pages/features/authentication/password-storage.adoc

@@ -213,7 +213,7 @@ There are convenience mechanisms to make this easier, but this is still not inte
 .Java
 [source,java,role="primary",attrs="-attributes"]
 ----
-User user = User.withDefaultPasswordEncoder()
+UserDetails user = User.withDefaultPasswordEncoder()
   .username("user")
   .password("password")
   .roles("user")
@@ -243,12 +243,12 @@ If you are creating multiple users, you can also reuse the builder:
 [source,java,role="primary"]
 ----
 UserBuilder users = User.withDefaultPasswordEncoder();
-User user = users
+UserDetails user = users
   .username("user")
   .password("password")
   .roles("USER")
   .build();
-User admin = users
+UserDetails admin = users
   .username("admin")
   .password("password")
   .roles("USER","ADMIN")

docs/modules/ROOT/pages/servlet/authentication/session-management.adoc

@@ -820,7 +820,7 @@ Authentication authentication = this.authenticationManager.authenticate(token);
 // ...
 SecurityContext context = SecurityContextHolder.createEmptyContext(); <1>
 context.setAuthentication(authentication); <2>
-SecurityContextHolder.setContext(authentication); <3>
+SecurityContextHolder.setContext(context); <3>
 ----
 ====