spring-session-sample-boot-findbyusername

[Ethns]

Issue Description:

encountering "Request method 'POST' not supported" error when terminate user session in spring-session-sample-boot-findbyusername sample application

release 2.2.2

Steps to reproduce the issue

1. start-up spring-session-samples/spring-session-sample-boot-findbyusername
   Follow below steps displayed on http://localhost:8080/ to delete the previous session
   
2. When click the terminate button to delete the session, the an error page comes up:
   
   

[rwinch]

Thanks for the report @Ethns! This is now fixed in master via fed318a.