Make AuthenticationFilter methods private

Fixes gh-7447

Author: jzheaux

web/src/main/java/org/springframework/security/web/authentication/AuthenticationFilter.java

@@ -158,15 +158,15 @@ private void unsuccessfulAuthentication(HttpServletRequest request, HttpServletR
 		this.failureHandler.onAuthenticationFailure(request, response, failed);
 	}
 
-	protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain,
+	private void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain,
 			Authentication authentication) throws IOException, ServletException {
 		SecurityContext context = SecurityContextHolder.createEmptyContext();
 		context.setAuthentication(authentication);
 		SecurityContextHolder.setContext(context);
 		this.successHandler.onAuthenticationSuccess(request, response, chain, authentication);
 	}
 
-	protected Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
+	private Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
 			throws AuthenticationException, IOException, ServletException {
 		Authentication authentication = this.authenticationConverter.convert(request);
 		if (authentication == null) {