Actually SimpleAuthorizingInterceptor works only with prepared SecurityContext (with resolved roles). Configured user roles map is checked only additionally to roles in context. It is possible to restrict access in configuration, but not extend it.
I see some use cases, where checking only configured roles also makes sense in SimpleAuthorizingInterceptor. Sample is authentication using SAML assertion without role assertion attribute and without TLS.
Proposal is to introduce boolean property "checkConfiguredRolesOnly" in SimpleAuthorizingInterceptor. If property is true, only configured roles will be checked, isUserInRole for SecurityContext will not be called.
By default property will be deactivated.
Patch is attached.