Is your feature request related to a problem? Please describe.
By default CORS blocks access to all headers except content-type. Custom headers need to be exposed using the header Access-Control-Expose-Headers.
Describe the solution you'd like
The CORSPolicy class should have a chainable method called exposeHeader which will take the header/pattern to be further used by building a comma seperated header value for Access-Control-Expose-Headers according to the spec.
Describe alternatives you've considered
I've implemented a simple RequestInterceptor which sets this header manually.
Additional context
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Headers