3 Mutually exclusive groups: how to declare required parameters?

I have 3 SetName mutually exclusive groups.
In every group I'd like to have required parameters.
1
p11 (required=true)
p12 (required=false)
2
p21 (required=true)
p22 (required=false)
3
p31 (required=true)
p32 (required=false)

By fact: the application detected group 2 it generated error that no required parameter p11.
But it is from group 1. I do not need it.
When I have declared all options Required=false it helped.

What I do wrong?