flectra/addons/project_timesheet_holidays/views/hr_holidays_views.xml

<?xml version="1.0" encoding="utf-8"?>
<flectra>

    <record id="hr_holiday_status_view_form_inherit" model="ir.ui.view">
        <field name="name">hr.holidays.status.form</field>
        <field name="model">hr.holidays.status</field>
        <field name="inherit_id" ref="hr_holidays.edit_holiday_status_form"/>
        <field name="arch" type="xml">
            <xpath expr="//group[@name='description']" position="after">
                <group name="timesheet" string="Timesheet">
                    <field name="timesheet_generate"/>
                    <field name="timesheet_project_id" attrs="{'invisible': [('timesheet_generate', '!=', True)], 'required': [('timesheet_generate', '=', True)]}" context="{'active_test': False}" groups="base.group_no_one"/>
                    <field name="timesheet_task_id" attrs="{'invisible': [('timesheet_generate', '!=', True)], 'required': [('timesheet_generate', '=', True)]}" context="{'active_test': False}" groups="base.group_no_one"/>
                </group>
            </xpath>
        </field>
    </record>

</flectra>