anchor.diff:  
   .Setting `SecurityContextHolder`
   ====
  -[source,java]
  +.Java
  +[source,java,role="primary"]
   ----
   SecurityContext context = SecurityContextHolder.createEmptyContext(); // <1>
   Authentication authentication =
  
positive.code: context.setAuthentication(authentication);
  
  SecurityContextHolder.setContext(context); // <3>
  ----
  ====
  
  
negative.code: 
  .Access Currently Authenticated User
  ====
  .Java
  [source,java,role="primary"]
  ----
  SecurityContext context = SecurityContextHolder.getContext();
  Authentication authentication = context.getAuthentication();
  String username = authentication.getName();
  Object principal = authentication.getPrincipal();
  Collection<? extends GrantedAuthority> authorities = authentication.getAuthorities();
  ----
  
  .Kotlin
  [source,kotlin,role="secondary"]
  ----
  val context = SecurityContextHolder.getContext()
  val authentication = context.authentication
  val username = authentication.name
  val principal = authentication.principal
  val authorities = authentication.authorities
  ----
  ====
  
  