I'm using Spring Framework 5.3.4 with Spring Boot 2.4.3.

I have a controller declared in this way:

@Controller @RequestMapping("${saml.sp.controller-base-mapping}") public class ServiceProviderController { /... }

So, the property saml.sp.controller-base-mapping is externalized in application.properties file: if its value is sp, this should be equivalent to: @RequestMapping("sp"). And indeed Spring Web MVC handles this well.

However, if I then use MvcUriComponentsBuilder to retrieve the corresponding URL:

MvcUriComponentsBuilder.fromController(ServiceProviderController.class).build().toURL();

This returns a UriComponents of: http://localhost:8081/${saml.sp.controller-base-mapping}

First problem: I would have expected the externalized property to be already resolved (so to get http://localhost:8081/sp), because this should be an expansion mechanism that comes BEFORE path variable expansion.

Indeed (and here comes the second problem), if I try to do:

MvcUriComponentsBuilder.fromController(ServiceProviderController.class).buildAndExpand("sp");

I then get a UriComponents of: http://localhost:8081/$sp

This is somewhat expected, since path variable expansion is another story and does not use the "$" marker.