content: package com.alibaba.fastjson2.v1issues.issue_1400;
  
  import com.alibaba.fastjson2.JSON;
  import com.alibaba.fastjson2.annotation.JSONField;
  import org.junit.jupiter.api.Test;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  
  public class Issue1474 {
      @Test
      public void test_for_issue() throws Exception {
          Map<String, Object> extraData = new HashMap<String, Object>();
          extraData.put("ext_1", null);
          extraData.put("ext_2", null);
  
          People p = new People();
          p.setId("001");
          p.setName("顾客");
          p.setExtraData(extraData);
  
          assertEquals("{\"id\":\"001\",\"name\":\"顾客\"}", JSON.toJSONString(p));
      }
  
      static class People {
          private String name;
          private String id;
          @JSONField(unwrapped = true)
          private Object extraData;
  
          public String getName() {
              return name;
          }
  
          public void setName(String name) {
              this.name = name;
          }
  
          public String getId() {
              return id;
          }
  
          public void setId(String id) {
              this.id = id;
          }
  
          public Object getExtraData() {
              return extraData;
          }
  
          public void setExtraData(Object extraData) {
              this.extraData = extraData;
          }
      }
  }
  