JSONParser doesn't support null, false, true

[colltoaction]

JSONParser is missing support for JSON values such as null, true, false. This means I can't use the compareJSON or other higher-level methods like Spring's WebTestClient.

E.g this won't work:

WebTestClient client = ...;
client.get().uri("/ips/42")
        //...
        .expectBody().json("null");

I can send a PR if a maintainer would want that.