List of Boolean is not populated in Action class

In my application, a user sends a request with this parameter : selectedLines[xx]=true where xx is a number. Stuts 2 should convert this parameter into this property : List<Boolean> selectedLines in my action class. The lenght of the list equals xx+1 and the list looks like this [null,null,.....,true];

Since I have upgraded Struts 2 to 2.5.10.1 From 2.3, that not works anymore if xx>256. The list is empty.