add testcase

src/test/java/com/alibaba/json/bvt/SpecialKeyTest2.java

+package com.alibaba.json.bvt;
+
+import java.util.Map;
+
+import org.junit.Assert;
+
+import com.alibaba.fastjson.JSON;
+
+import junit.framework.TestCase;
+
+public class SpecialKeyTest2 extends TestCase {
+    public void test_0() throws Exception {
+        Model model = JSON.parseObject("{\"items\":{\"1\":{},\"1001\":{}},\"items1\":{\"$ref\":\"$.items\"}}", Model.class);
+        Assert.assertEquals(2, model.items.size());
+        Assert.assertNotNull(model.items.get(1L));
+        Assert.assertNotNull(model.items.get(1001L));
+        Assert.assertSame(model.items, model.items1);
+    }
+    
+    public static class Model {
+        public Map<Long, Item> items;
+        public Map<Long, Item> items1;
+    }
+    
+    public static class Item {
+    }
+}