Treeview.CheckedNodes contains indices of undelying list making them
useless for further operations. I was unable to access said list, and were I be able to, it would add another
complexity for finding correct values, which are actually stored in DataIdFields used to build tree in the first place, above all those are primary keys from db table.
In case you are wondering, correct values are stored in Request.Form under the appropriate keys eg. Treeview.ClientId"+"_Checkbox_"+DataIdField.IMO storing value as part of key and creating as many request parameters is