content: package com.alibaba.fastjson2.autoType;
  
  import com.alibaba.fastjson2.JSON;
  import com.alibaba.fastjson2.JSONObject;
  import com.alibaba.fastjson2.JSONReader;
  import com.alibaba.fastjson2.JSONWriter;
  import com.alibaba.fastjson2.filter.Filter;
  import org.junit.jupiter.api.Test;
  
  import java.nio.charset.StandardCharsets;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Set;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  
  public class SetTest {
      @Test
      public void test0() throws Exception {
          Bean bean = new Bean();
          bean.content = new HashSet<>();
  
          String str = JSON.toJSONString(bean, JSONWriter.Feature.WriteClassName);
          assertEquals("{\"@type\":\"com.alibaba.fastjson2.autoType.SetTest$Bean\",\"content\":Set[]}", str);
          Bean bean1 = JSON.parseObject(str, Bean.class);
          assertNotNull(bean1.content);
          assertEquals(0, bean1.content.size());
      }
  
      public static class Bean {
          public Collection<String> content;
      }
  
      @Test
      public void test1() throws Exception {
          String str = "{\"content\":Set[]}";
          Bean bean1 = JSON.parseObject(str, Bean.class);
          assertNotNull(bean1.content);
          assertEquals(0, bean1.content.size());
      }
  
      @Test
      public void test2() throws Exception {
          String str = "{\"content\":Set[]}";
          JSONObject object = JSON.parseObject(str);
          assertNotNull(object.get("content"));
          assertEquals(0, object.getJSONArray("content").size());
      }
  
      @Test
      public void test2Bytes() throws Exception {
          String str = "{\"content\":Set[]}";
          byte[] bytes = str.getBytes(StandardCharsets.UTF_8);
  
          {
              JSONObject object = JSON.parseObject(bytes);
              assertNotNull(object.get("content"));
              assertEquals(0, object.getJSONArray("content").size());
          }
          {
              JSONObject object = JSON.parseObject(bytes, 0, bytes.length, StandardCharsets.US_ASCII);
              assertNotNull(object.get("content"));
              assertEquals(0, object.getJSONArray("content").size());
          }
      }
  
      @Test
      public void test3() throws Exception {
          String str = "{\"@type\":\"java.util.HashMap\",\"content\":Set[]}";
          HashMap map = (HashMap) JSON.parseObject(str, Object.class);
          assertNotNull(map.get("content"));
          Set set = (Set) map.get("content");
          assertEquals(0, set.size());
      }
  
      @Test
      public void test4() throws Exception {
          String str = "{\"@type\":\"java.util.HashMap\",\"content\":Set[]}";
  
          Filter file = JSONReader.autoTypeFilter("java.util.HashMap");
          HashMap map = (HashMap) JSON.parseObject(str, Object.class, file);
          assertNotNull(map.get("content"));
          Set set = (Set) map.get("content");
          assertEquals(0, set.size());
      }
  }
  