commons-validator design clarification

[Arik Levin ( Tikal )]

Hi all.
 
            I can't figure out, why all the entities (at commons-validator
package) implemented extendable except FormSet which has private members???
            (By saying entities I'm referring to Form; Field; Arg; Msg) 
            I have some bug fixes and ideas I want to share with. But I need
first to finish my projects, I have some deadlines.
            My intentions were to extend specific objects and keep
commons-validator,jar  untouched.
 
            So if there's a design reason for this Ok, than.
            But if its members can be protected instead of private, I'll be
glad to hear that.