Hello Mchakkah Alaa,

I think you should try like with below code

@api.model
def default_get(self, fields):
res = super(HrRefusWizard, self).default_get(fields)
employee = self.env['hr.employee'].browse(self._context['active_id'])
if lead:
res['employee_id'] = employee.id
return res

refus = fields.Text(string='Comentaire de refus', required=False)
employee_id = fields.Many2one('hr.employee', string='Employee', required=True)

Thanks & Regards,
Email: odoo@aktivsoftware.com
Skype: kalpeshmaheshwari

Facing the same problem for One2many pop up. All the examples are given using wizard, not using pop up that appears in One2many relationship. 

No it’s not working I just tried it!

I think you have to declare the fields above default get method.