title: Drupal: How to use fieldsets in hook_field_widget_form
body: <p>So I have my hook_field_schema defining columns, and hook_field_widget_form is set up and saving all of the column values correctly.</p>
  
  <p>But as soon as I put two of the fields inside of a fieldset, those values never save or get updated. I've tried setting #tree => FALSE all over the place and that isn't working either.</p>
  
  <p>What am I missing? Is it just unsupported? Should I be using a form_alter hook or something to move them into a fieldset?</p>