Add @EnableOAuth2Sso and spring.oauth2.sso.*

User can enable OAuth2 SSO by declaring the intent (@EnableOAuth2Sso)
and also configuring the client properties (spring.oauth2.client.*).
The spring.oauth2.sso.* are only needed to change the path for the
login (defaults to /login) - any other security configuration for the
protected resources can be added in a WebSecurityConfigurerAdapter
which carries the @EnableOAuth2Sso annotation.

spring-boot-samples/spring-boot-sample-web-secure-github/src/main/resources/application.yml

@@ -0,0 +1,11 @@
+spring:
+  oauth2:
+    client:
+      clientId: bd1c0a783ccdd1c9b9e4
+      clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1
+      accessTokenUri: https://github.com/login/oauth/access_token
+      userAuthorizationUri: https://github.com/login/oauth/authorize
+      clientAuthenticationScheme: form
+    resource:
+      userInfoUri: https://api.github.com/user
+      preferTokenInfo: false