centralize auth logic

AuthorizationLogic.java

public static authorize(JsonObject authInfo, Handler<User> onAuthorized, Handler<Throwable> onFailure) {
  return res -> {
  	if (res.succeeded()) {
    	        User user = res.result();
    	        user.isAuthorised("newsletter:edit:13", res2 -> {
  			if (res2.succeeded()) {
    			        boolean hasPermission = res2.result();
    			        if(hasPermission){
                    onAuthorized.handle(user);
    			        }
    			        else{
                    onFailure.handle(new AuthorizationException());
    			        }
    			        
  			} else {
  			  onFailure.handle(res2.cause());
  			}
		});
  	} else {
      onFailure.handle(res.cause());
  	}    
  }
}

YourApp.java

import static AuthorizationLogic.authorize;

authorize(authInfo, user -> {
  user.greet();
  // do what you want to 
}, failure -> {
  if (!(failure instanceof AuthorizationException)) {
    log.error("Something went wrong");
    // notify client (503 ?)
  } else {
    // context.fail(401); 
    // insult user
    // ban him...
  }
});