Expose Configuration for ControllerLinkBuilder

ControllerLinkBuilder uses some configurable components but they are not exposed for clients. For example, if one is using a domain object in a controller method and wants to generate a URI from the method, they cannot do so. For example:

BookSearch search = new BookSearch("author:johnson genre:technical");
Link link = linkTo(methodOn(BookController.class).fetchBooks(search)).withSelfRel();

The above, without the ability to get into the internal factory of ControllerLinkBuilder and configure a custom UriComponentsContributor, the resulting URI would look like this:

/books

When it is expected to look like this:

/books?search=author:johnson%20genre:technical

I've tried a bunch of techniques to solve this and so far the only solution is very bad: create a bean that will use reflection to get access to the internal factory and register UirComponentsContributors during startup.

Start by locating ControllerLinkBuilder and its internal factory, then trace how UriComponentsContributor instances are configured. Define a supported way for clients to register a custom contributor without reflection, and verify that the BookSearch example produces the expected encoded query URI.