Validation on checkbox and input field in jsf

Question

I have a list of checkboxes and one input field in two separate panelgrids. I have to do validation such that if none of the checkboxes are checked, the input field should be mandatory. My two checkboxes are inside a for each loop in one panelgrid and input field is in other panelgrid. tried to use multivalidator for both these fields but getting only first checkbox value from list. for others it is always false whether checked or not. how could I check whether each one is checked or not.Anyone has any idea? Could not share the code due to security policies.