Added Marianum Message pdf reader and backend

lib/api/mhsl/message/getMessages/getMessagesResponse.dart

@@ -0,0 +1,27 @@
+import 'package:json_annotation/json_annotation.dart';
+import 'package:marianum_mobile/api/apiResponse.dart';
+
+part 'getMessagesResponse.g.dart';
+
+@JsonSerializable(explicitToJson: true)
+class GetMessagesResponse extends ApiResponse {
+  String base;
+  Set<GetMessagesResponseObject> messages;
+
+  GetMessagesResponse(this.base, this.messages);
+
+  factory GetMessagesResponse.fromJson(Map<String, dynamic> json) => _$GetMessagesResponseFromJson(json);
+  Map<String, dynamic> toJson() => _$GetMessagesResponseToJson(this);
+}
+
+@JsonSerializable(explicitToJson: true)
+class GetMessagesResponseObject {
+  String name;
+  String date;
+  String url;
+
+  GetMessagesResponseObject(this.name, this.date, this.url);
+
+  factory GetMessagesResponseObject.fromJson(Map<String, dynamic> json) => _$GetMessagesResponseObjectFromJson(json);
+  Map<String, dynamic> toJson() => _$GetMessagesResponseObjectToJson(this);
+}