add testcase for issue #555

core/src/test/java/com/alibaba/fastjson2/issues/Issue555.java

@@ -0,0 +1,28 @@
+package com.alibaba.fastjson2.issues;
+
+import com.alibaba.fastjson2.JSON;
+import org.junit.jupiter.api.Test;
+
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class Issue555 {
+    @Test
+    public void test() {
+        Bean bean = JSON.parseObject("{\"values\":Set[]}", Bean.class);
+        assertTrue(bean.values.isEmpty());
+    }
+
+    public static class Bean {
+        private Set<String> values;
+
+        public Set<String> getValues() {
+            return values;
+        }
+
+        public void setValues(Set<String> values) {
+            this.values = values;
+        }
+    }
+}