added default static method in ludbo

src/Utils/LuDbo.php

@@ -22,4 +22,14 @@ abstract class LuDbo implements \JsonSerializable {
         }
         return $obj;
     }
+
+    public static function jsonDeserialize($json)
+    {
+        return null;
+    }
+
+    public static function generateSample()
+    {
+        return null;
+    }
 }