#126: fixed last tests

Author: jorre127

test/writer/object_model_writer/to-json-from-json-handler/config.txt

@@ -2,12 +2,13 @@ Person:
   path: user/custom_person.dart
   type: object
   properties:
-    address: Address
+    address:
+      type: Address
+      toJson: handleToJson
+      fromJson: handleFromJson
 
 Address:
   type: object
   properties:
     streetName:
-      type: String
-      toJson: handleToJson
-      fromJson: handleFromJson
+      type: String

test/writer/object_model_writer/to-json-from-json-handler/output.txt

@@ -7,7 +7,7 @@ part 'person.g.dart';
 
 @JsonSerializable(explicitToJson: true)
 class Person {
-  @JsonKey(name: 'address', required: true, fromJson: handleFromJson, toJson: handleToJson)
+  @JsonKey(name: 'address', required: true, includeIfNull: false, fromJson: handleFromJson, toJson: handleToJson)
   final Address address;
 
   const Person({