deepen webfinger, endpoint is looser

closes mitreid-connect#1008

Author: jricher

openid-connect-server/src/main/java/org/mitre/discovery/web/DiscoveryEndpoint.java

@@ -101,10 +101,13 @@ public String apply(Algorithm alg) {
 }
 };
 
-@RequestMapping(value={"/" + WEBFINGER_URL},
-params={"resource", "rel=http://openid.net/specs/connect/1.0/issuer"}, produces = MediaType.APPLICATION_JSON_VALUE)
-public String webfinger(@RequestParam("resource") String resource, Model model) {
+@RequestMapping(value={"/" + WEBFINGER_URL}, produces = MediaType.APPLICATION_JSON_VALUE)
+public String webfinger(@RequestParam("resource") String resource, @RequestParam(value = "rel", required = false) String rel, Model model) {
 
+if (!Strings.isNullOrEmpty(rel) && !rel.equals("https://github.com/mitreid-connect/OpenID-Connect-Java-Spring-Server/issues")) {
+logger.warn("Responding to webfinger request for non-OIDC relation: " + rel);
+}
+
 if (!resource.equals(config.getIssuer())) {
 // it's not the issuer directly, need to check other methods