this sample project login example github, google, facebook, kakao
spring.security.oauth2.client.registration.github.client-id=<user client-id>
spring.security.oauth2.client.registration.github.client-secret=<user secret>
custom oauth2 login
spring.security.oauth2.client.registration.kakao.client-id=<user client-id>
spring.security.oauth2.client.registration.kakao.client-secret=<user secret>
##..
Sample : application.properties
