Start to integrate data conservation policy

lib/models/data_conservation_policy_settings.dart

@@ -0,0 +1,21 @@
+/// Data conservation policy settings
+///
+/// @author Pierre Hubert
+
+class DataConservationPolicySettings {
+  int inactiveAccountLifeTime;
+  int notificationLifetime;
+  int commentsLifetime;
+  int postsLifetime;
+  int conversationMessagesLifetime;
+  int likesLifetime;
+
+  DataConservationPolicySettings({
+    this.inactiveAccountLifeTime,
+    this.notificationLifetime,
+    this.commentsLifetime,
+    this.postsLifetime,
+    this.conversationMessagesLifetime,
+    this.likesLifetime,
+  });
+}

lib/models/server_config.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/widgets.dart';
+
+/// Server static configuration
+///
+/// @author Pierre Hubert
+
+class ServerDataConservationPolicy {
+  final int minInactiveAccountLifetime;
+  final int minNotificationLifetime;
+  final int minCommentsLifetime;
+  final int minPostsLifetime;
+  final int minConversationMessagesLifetime;
+  final int minLikesLifetime;
+
+  const ServerDataConservationPolicy({
+    @required this.minInactiveAccountLifetime,
+    @required this.minNotificationLifetime,
+    @required this.minCommentsLifetime,
+    @required this.minPostsLifetime,
+    @required this.minConversationMessagesLifetime,
+    @required this.minLikesLifetime,
+  })  : assert(minInactiveAccountLifetime != null),
+        assert(minNotificationLifetime != null),
+        assert(minCommentsLifetime != null),
+        assert(minPostsLifetime != null),
+        assert(minConversationMessagesLifetime != null),
+        assert(minLikesLifetime != null);
+}
+
+class ServerConfig {
+  final ServerDataConservationPolicy dataConservationPolicy;
+
+  const ServerConfig({
+    @required this.dataConservationPolicy,
+  }) : assert(dataConservationPolicy != null);
+}