[BUG] JSON.toJSON(x) should be equivalent to JSON.parse(JSON.toJSONString(x)), but misses typeKey

[blutorange]

问题描述

JSON.toJSON(x) should be equivalent to JSON.parse(JSON.toJSONString(x)). But JSON.toJSON does not include the type key when using @JsonType(typeKey = "type").

环境信息

• 版本信息： Fastjson2 2.0.53

重现步骤

如何操作可以重现该问题：

git clone https://github.com/blutorange/issue-repro
cd issue-repro
git checkout issue-fastjson-tojson-missing-type-key
mvn test

The test fails:

org.opentest4j.AssertionFailedError: 
Expected :{"type":"circle","radius":5}
Actual   :{"radius":5}

For reference, the classes are:

@JSONType(typeKey = "type", seeAlso = {Shape.Triangle.class, Shape.Circle.class})
public class Shape {
    @JSONType(typeKey = "type", typeName = "circle", serializeFeatures = JSONWriter.Feature.WriteClassName)
    public static class Circle extends Shape {
        private int radius;
        public int getRadius() { return radius; }
        public void setRadius(int radius) { this.radius = radius; }
    }
}

and the test is

    @Test
    public void issueFastJson2_ToJson_Differs_From_ToJsonString() {
        var circle = new Shape.Circle();
        circle.setRadius(5);
        assertEquals(JSON.parse(JSON.toJSONString(circle)), JSON.toJSON(circle));
    }

期待的正确结果

The JSONObject returned by JSON.toJSON should include "type":"circle".