Adding JSON example. (#1)

jsonexample/lib/json_serializable/serializable_complex_object.dart

@@ -0,0 +1,35 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:json_annotation/json_annotation.dart';
+import 'package:jsonexample/json_serializable/serializable_simple_object.dart';
+
+part 'serializable_complex_object.g.dart';
+
+@JsonSerializable()
+class SerializableComplexObject extends Object
+    with _$SerializableComplexObjectSerializerMixin {
+  SerializableComplexObject({
+    this.aString,
+    this.anInt,
+    this.aDouble,
+    this.anObject,
+    this.aListOfStrings,
+    this.aListOfInts,
+    this.aListOfDoubles,
+    this.aListOfObjects,
+  });
+
+  final String aString;
+  final int anInt;
+  final double aDouble;
+  final SerializableSimpleObject anObject;
+  final List<String> aListOfStrings;
+  final List<int> aListOfInts;
+  final List<double> aListOfDoubles;
+  final List<SerializableSimpleObject> aListOfObjects;
+
+  factory SerializableComplexObject.fromJson(Map<String, dynamic> json) =>
+      _$SerializableComplexObjectFromJson(json);
+}