Add Resource.lid

Author: f3ath

lib/src/document/new_resource.dart

@@ -2,17 +2,21 @@ import 'package:json_api/src/document/resource_properties.dart';
 
 /// A set of properties for a to-be-created resource which does not have the id yet.
 class NewResource with ResourceProperties {
-  NewResource(this.type, {this.id});
+  NewResource(this.type, {this.id, this.lid});
 
   /// Resource type
   final String type;
 
-  /// Nullable. Resource id.
+  /// Resource id.
   final String? id;
 
+  /// Local resource id.
+  final String? lid;
+
   Map<String, Object> toJson() => {
         'type': type,
         if (id != null) 'id': id!,
+        if (lid != null) 'lid': lid!,
         if (attributes.isNotEmpty) 'attributes': attributes,
         if (relationships.isNotEmpty) 'relationships': relationships,
         if (meta.isNotEmpty) 'meta': meta,

test/unit/document/new_resource_test.dart

@@ -10,7 +10,7 @@ void main() {
           jsonEncode({'type': 'test_type'}));
 
       expect(
-          jsonEncode(NewResource('test_type')
+          jsonEncode(NewResource('test_type', id: 'test_id', lid: 'test_lid')
             ..meta['foo'] = [42]
             ..attributes['color'] = 'green'
             ..relationships['one'] =
@@ -21,6 +21,8 @@ void main() {
                   ..meta['many'] = 1)),
           jsonEncode({
             'type': 'test_type',
+            'id': 'test_id',
+            'lid': 'test_lid',
             'attributes': {'color': 'green'},
             'relationships': {
               'one': {