Struts2 validation of indexed textfields possible?

Question

Hello.

What is the correct way of validating indexed textfields with the built in validation framework in Struts2?

For example sth. like:

<s:textfield key="names[0]" />
<s:textfield key="names[1]" />
<s:textfield key="names[1]" />

I don't want to replicate all the simple built in validators just for validating such simple indexed fields.

Thank you for your help.