code: @Bean
  	public AuthorProvider authorProvider() {
  		return () -> {
  			final SecurityContext context = SecurityContextHolder.getContext();
  			if (context != null && context.getAuthentication() != null) {
  				return context.getAuthentication().getPrincipal().toString();
  			} else {
  				return "system";
  			}
  		};
  	}
docs: Author provider.
  
  @return the author provider