public List<String> getMessages() { List<String> messages = new ArrayList<String>(); for (Location l : extra.keySet()) { String location = l.location.equals("") ? "" : l.location + "."; String message = "attribute " + location + l.key + " is unexpected"; messages.add(message); } for (Location l : invalidType.keySet()) { String location = l.location.equals("") ? "" : l.location + "."; String message = "attribute " + location + l.key + " is not of type `" + invalidType.get(l) + "`"; messages.add(message); } for (Location l : missing) { String location = l.location.equals("") ? "" : l.location + "."; String message = "attribute " + location + l.key + " is missing"; messages.add(message); } return messages; }