linter and lint fixes

flutter/lib/models/api_error.dart

@@ -13,10 +13,10 @@ class APIError {
 
   factory APIError.fromJson(Map<String, dynamic> json) {
     return APIError(
-      success: json['success'],
-      error: json['error'],
-      errhighlight: json['errhighlight'],
-      message: json['message'],
+      success: json['success'] as String,
+      error: json['error'] as String,
+      errhighlight: json['errhighlight'] as String,
+      message: json['message'] as String,
     );
   }
 }

flutter/lib/models/channel.dart

@@ -25,15 +25,15 @@ class Channel {
 
   factory Channel.fromJson(Map<String, dynamic> json) {
     return Channel(
-      channelID: json['channel_id'],
-      ownerUserID: json['owner_user_id'],
-      internalName: json['internal_name'],
-      displayName: json['display_name'],
-      descriptionName: json['description_name'],
-      subscribeKey: json['subscribe_key'],
-      timestampCreated: json['timestamp_created'],
-      timestampLastSent: json['timestamp_lastsent'],
-      messagesSent: json['messages_sent'],
+      channelID: json['channel_id'] as String,
+      ownerUserID: json['owner_user_id'] as String,
+      internalName: json['internal_name'] as String,
+      displayName: json['display_name'] as String,
+      descriptionName: json['description_name'] as String?,
+      subscribeKey: json['subscribe_key'] as String?,
+      timestampCreated: json['timestamp_created'] as String,
+      timestampLastSent: json['timestamp_lastsent'] as String?,
+      messagesSent: json['messages_sent'] as int,
     );
   }
 }
@@ -56,20 +56,20 @@ class ChannelWithSubscription extends Channel {
 
   factory ChannelWithSubscription.fromJson(Map<String, dynamic> json) {
     return ChannelWithSubscription(
-      channelID: json['channel_id'],
-      ownerUserID: json['owner_user_id'],
-      internalName: json['internal_name'],
-      displayName: json['display_name'],
-      descriptionName: json['description_name'],
-      subscribeKey: json['subscribe_key'],
-      timestampCreated: json['timestamp_created'],
-      timestampLastSent: json['timestamp_lastsent'],
-      messagesSent: json['messages_sent'],
-      subscription: Subscription.fromJson(json['subscription']),
+      channelID: json['channel_id'] as String,
+      ownerUserID: json['owner_user_id'] as String,
+      internalName: json['internal_name'] as String,
+      displayName: json['display_name'] as String,
+      descriptionName: json['description_name'] as String?,
+      subscribeKey: json['subscribe_key'] as String?,
+      timestampCreated: json['timestamp_created'] as String,
+      timestampLastSent: json['timestamp_lastsent'] as String?,
+      messagesSent: json['messages_sent'] as int,
+      subscription: Subscription.fromJson(json['subscription'] as Map<String, dynamic>),
     );
   }
 
   static List<ChannelWithSubscription> fromJsonArray(List<dynamic> jsonArr) {
-    return jsonArr.map<ChannelWithSubscription>((e) => ChannelWithSubscription.fromJson(e)).toList();
+    return jsonArr.map<ChannelWithSubscription>((e) => ChannelWithSubscription.fromJson(e as Map<String, dynamic>)).toList();
   }
 }

flutter/lib/models/message.dart

@@ -31,26 +31,26 @@ class Message {
 
   factory Message.fromJson(Map<String, dynamic> json) {
     return Message(
-      messageID: json['message_id'],
-      senderUserID: json['sender_user_id'],
-      channelInternalName: json['channel_internal_name'],
-      channelID: json['channel_id'],
-      senderName: json['sender_name'],
-      senderIP: json['sender_ip'],
-      timestamp: json['timestamp'],
-      title: json['title'],
-      content: json['content'],
-      priority: json['priority'],
-      userMessageID: json['usr_message_id'],
-      usedKeyID: json['used_key_id'],
-      trimmed: json['trimmed'],
+      messageID: json['message_id'] as String,
+      senderUserID: json['sender_user_id'] as String,
+      channelInternalName: json['channel_internal_name'] as String,
+      channelID: json['channel_id'] as String,
+      senderName: json['sender_name'] as String,
+      senderIP: json['sender_ip'] as String,
+      timestamp: json['timestamp'] as String,
+      title: json['title'] as String,
+      content: json['content'] as String,
+      priority: json['priority'] as int,
+      userMessageID: json['usr_message_id'] as String,
+      usedKeyID: json['used_key_id'] as String,
+      trimmed: json['trimmed'] as bool,
     );
   }
 
-  static fromPaginatedJsonArray(Map<String, dynamic> data, String keyMessages, String keyToken) {
+  static (String, List<Message>) fromPaginatedJsonArray(Map<String, dynamic> data, String keyMessages, String keyToken) {
     final npt = data[keyToken] as String;
 
-    final messages = (data[keyMessages] as List<dynamic>).map<Message>((e) => Message.fromJson(e)).toList();
+    final messages = (data[keyMessages] as List<dynamic>).map<Message>((e) => Message.fromJson(e as Map<String, dynamic>)).toList();
 
     return (npt, messages);
   }

flutter/lib/models/subscription.dart

@@ -19,13 +19,13 @@ class Subscription {
 
   factory Subscription.fromJson(Map<String, dynamic> json) {
     return Subscription(
-      subscriptionID: json['subscription_id'],
-      subscriberUserID: json['subscriber_user_id'],
-      channelOwnerUserID: json['channel_owner_user_id'],
-      channelID: json['channel_id'],
-      channelInternalName: json['channel_internal_name'],
-      timestampCreated: json['timestamp_created'],
-      confirmed: json['confirmed'],
+      subscriptionID: json['subscription_id'] as String,
+      subscriberUserID: json['subscriber_user_id'] as String,
+      channelOwnerUserID: json['channel_owner_user_id'] as String,
+      channelID: json['channel_id'] as String,
+      channelInternalName: json['channel_internal_name'] as String,
+      timestampCreated: json['timestamp_created'] as String,
+      confirmed: json['confirmed'] as bool,
     );
   }
 }

flutter/lib/models/user.dart

@@ -41,24 +41,24 @@ class User {
 
   factory User.fromJson(Map<String, dynamic> json) {
     return User(
-      userID: json['user_id'],
-      username: json['username'],
-      timestampCreated: json['timestamp_created'],
-      timestampLastRead: json['timestamp_lastread'],
-      timestampLastSent: json['timestamp_lastsent'],
-      messagesSent: json['messages_sent'],
-      quotaUsed: json['quota_used'],
-      quotaRemaining: json['quota_remaining'],
-      quotaPerDay: json['quota_max'],
-      isPro: json['is_pro'],
-      defaultChannel: json['default_channel'],
-      maxBodySize: json['max_body_size'],
-      maxTitleLength: json['max_title_length'],
-      defaultPriority: json['default_priority'],
-      maxChannelNameLength: json['max_channel_name_length'],
-      maxChannelDescriptionLength: json['max_channel_description_length'],
-      maxSenderNameLength: json['max_sender_name_length'],
-      maxUserMessageIDLength: json['max_user_message_id_length'],
+      userID: json['user_id'] as String,
+      username: json['username'] as String?,
+      timestampCreated: json['timestamp_created'] as String,
+      timestampLastRead: json['timestamp_lastread'] as String?,
+      timestampLastSent: json['timestamp_lastsent'] as String?,
+      messagesSent: json['messages_sent'] as int,
+      quotaUsed: json['quota_used'] as int,
+      quotaRemaining: json['quota_remaining'] as int,
+      quotaPerDay: json['quota_max'] as int,
+      isPro: json['is_pro'] as bool,
+      defaultChannel: json['default_channel'] as String,
+      maxBodySize: json['max_body_size'] as int,
+      maxTitleLength: json['max_title_length'] as int,
+      defaultPriority: json['default_priority'] as int,
+      maxChannelNameLength: json['max_channel_name_length'] as int,
+      maxChannelDescriptionLength: json['max_channel_description_length'] as int,
+      maxSenderNameLength: json['max_sender_name_length'] as int,
+      maxUserMessageIDLength: json['max_user_message_id_length'] as int,
     );
   }
 }