I am using Jenkins 2.190.3. when I tried to integrate the authentication with GitHub OAuth Plugin version 0.33. when I tried to configure the same I am getting an error like 
 
java.lang.ClassCastException: org.acegisecurity.providers.anonymous.AnonymousAuthenticationToken cannot be cast to org.jenkinsci.plugins.GithubAuthenticationTokenjava.lang.ClassCastException: org.acegisecurity.providers.anonymous.AnonymousAuthenticationToken cannot be cast to org.jenkinsci.plugins.GithubAuthenticationToken at org.jenkinsci.plugins.GithubSecurityRealm.loadGroupByGroupname(GithubSecurityRealm.java:784) at org.jenkinsci.plugins.matrixauth.AuthorizationContainerDescriptor.doCheckName(AuthorizationContainerDescriptor.java:169) at hudson.security.GlobalMatrixAuthorizationStrategy$DescriptorImpl.doCheckName(GlobalMatrixAuthorizationStrategy.java:222) at java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:627)_