fix:空数组才返回括号

@@ -6,7 +6,11 @@ class Json
 {
     public static function marshal(array $array)
     {
-        return \json_encode($array, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_FORCE_OBJECT);
+        $flag = JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE;
+        if (0 === count($array)) {
+            $flag |= JSON_FORCE_OBJECT;
+        }
+        return \json_encode($array, $flag);
     }
 
     public static function unmarshal(string $value, $associative = true)