title: related field on odoo?
body: <p>how to add a field related on odoo <br/>
  I would like to add a text field on stock.move related to stock.picking origin field <br/>
  I tried this :</p>
  
  <pre><code>_columns={       
      'sourcebl': fields.related('picking_id', 'origin',  type='char', relation='stock.picking', string='Class Description', store=True, readonly=True),
            }
  </code></pre>
  
  <p>do you have any Idea </p>