GUACAMOLE-1809: Remove obsolete license information

The Spring framework is no longer used.

extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/RequestValidationService.java

@@ -52,7 +52,7 @@ public class RequestValidationService {
      * @param confService
      *     The (mock) instance of ConfigurationService
      */
-    private RequestValidationService(ConfigurationService confService) {
+    public RequestValidationService(ConfigurationService confService) {
         this.confService = confService;
     }