Enhance InstanceOfPatternMatch to cover method invocations as well

What problem are you trying to solve?

I've come across

if (authentication.getPrincipal() instanceof UserDetails) {
    UserDetails springSecurityUser = (UserDetails) authentication.getPrincipal();
    return springSecurityUser.getUsername();
}

which is currently not covered

Describe the solution you'd like

if (authentication.getPrincipal() instanceof UserDetails springSecurityUser) {
    return springSecurityUser.getUsername();
}

Start by locating the InstanceOfPatternMatch recipe and its existing tests, then inspect how it handles instanceof expressions involving local variables. Add coverage for the authentication.getPrincipal() method-invocation example and verify that the transformation produces pattern matching with the bound UserDetails variable.