content: package com.alibaba.fastjson2.issues_2500;
  
  import com.alibaba.fastjson2.JSON;
  import com.alibaba.fastjson2.JSONWriter;
  import com.alibaba.fastjson2.filter.PropertyPreFilter;
  import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class Issue2590A {
      @Test
      public void test_map1_childItem() {
          Bean bean = new Bean();
          bean.map1 = new HashMap<String, Item>() {
              {
                  put("childItem", new Item(301));
                  put("childItem1", new Item(401));
              }
          };
  
          List<String> paths = new ArrayList<>();
          FilterDemo filter = new FilterDemo(paths);
  
          JSON.toJSONString(bean, filter, JSONWriter.Feature.ReferenceDetection);
          assertTrue(paths.contains("$.map1.childItem"));
          assertTrue(paths.contains("$.map1.childItem1"));
      }
  
      public static class FilterDemo
              implements PropertyPreFilter {
          private final List<String> paths;
  
          public FilterDemo(List<String> paths) {
              this.paths = paths;
          }
  
          @Override
          public boolean process(JSONWriter writer, Object source, String name) {
              String path = writer.getPath();
              paths.add(path);
              return true;
          }
      }
  
      public static class Bean {
          public Map<String, Item> map1;
      }
  
      public static class Item {
          public int id;
  
          public Item() {
          }
  
          public Item(int id) {
              this.id = id;
          }
      }
  }
  