你必须扩展你的班级样本列表

Class SampleList.java
public class SampleList {
    private Integer categoryId;
    private String  categoryName;
    private SubCategory subCategory;
//getter setter

当然，在返回列表之前，必须在samplelist项中设置正确的子类别。
如果你不想破坏你的samplelist类，当然你可以添加一层dto对象并在它们之间Map，或者直接操作响应，比如用responsebodyadvice

方法：1

public class SampleList
{
    private Integer categoryId;
    private String categoryName;

    // Getter and Setter
}

public class SampleList2
{
   private String name;
   // Getter and Setter
}

//在不Map两个不同类的情况下获取json值的逻辑

private void getJsonValue() throws JsonProcessingException, JSONException
{
    SampleList sampleList = new SampleList();
    sampleList.setCategoryId(1);
    sampleList.setCategoryName("cat 1");

    String sampleListJson = new ObjectMapper().writeValueAsString(sampleList);

    SampleList2 sampleList2 = new SampleList2();
    sampleList2.setName("Sub category");

    String valueOfSample2 = new ObjectMapper().writeValueAsString(sampleList2);

    JSONObject sampleListJsonObj = new JSONObject(sampleListJson); // for class SampleList
    JSONObject sampleList2JsonObj = new JSONObject(valueOfSample2); // for class SampleList2

    sampleListJsonObj.put("subCategory", sampleList2JsonObj);

    System.out.println(sampleListJsonObj.toString());
}

方法：2

public class SampleList
{
    private Integer categoryId;
    private String categoryName;
    private SampleList2 subCategory;

    // Getter and Setter
}

public class SampleList2
{
   private String name;
   // Getter and Setter
}

//上面提到的Map两个类的逻辑

private static void getJsonValue() throws JsonProcessingException
{
    SampleList sampleList = new SampleList();
    sampleList.setCategoryId(1);
    sampleList.setCategoryName("cat 1");

    SampleList2 sampleList2 = new SampleList2();
    sampleList2.setName("Sub category");

    sampleList.setSubCategory(sampleList2);

    String jsonString = new ObjectMapper().writeValueAsString(sampleList);

    System.out.println(jsonString.toString());
}

如果您有任何问题，请告诉我。
谢谢您。