title: Spring Security OAuth2: InsufficientAuthenticationException
body: <p>First of all, I disabled basic auth:</p>
  
  <pre><code>security.basic.enabled=false
  </code></pre>
  
  <p>Then I access the authorization page:</p>
  
  <pre><code>http://localhost:8080/oauth/authorize?client_id=client&amp;response_type=code&amp;redirect_uri=http://www.baidu.com
  </code></pre>
  
  <p>I got following exception:</p>
  
  <pre><code>org.springframework.security.authentication.InsufficientAuthenticationException: User must be authenticated with Spring Security before authorization can be completed.
      at org.springframework.security.oauth2.provider.endpoint.AuthorizationEndpoint.authorize(AuthorizationEndpoint.java:138) ~[spring-security-oauth2-2.0.10.RELEASE.jar:na]
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_45]
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_45]
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_45]
      at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_45]
      at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
      at ...
  </code></pre>
  
  <p>I don't understand why I have to do authentication first before OAuth?</p>