Custom ELResolver ordering after javax.el to jakarta.el migration

Goal: confirm whether an application-registered custom ELResolver runs before or after the standard implicit-object resolvers when the expression base is null, and whether that behavior changes across the javax.el to jakarta.el compatibility boundary.

Resolver chain position and null-base handling are implementation-dependent. Package migration can alter service-loader registrations and expression behavior even when the API looks similar. Authentication state and expired credentials must be enforced outside EL resolution, not inside resolver caching or expression compilation.

Questions: Does the container guarantee resolver order across the javax.el to jakarta.el boundary? Does a null base reach the custom resolver before implicit-object resolvers, or does it throw PropertyNotFoundException first? Is cached resolver state invalidated when the security context changes?