<?xml version="1.0"?>
<data><xpath expr="//button[@name='action_invoice_sent'][hasclass('oe_highlight')]" position="attributes">
                <attribute name="invisible" add="state != 'posted' or is_being_sent or invoice_pdf_report_id or not can_send_as_self_invoice" separator=" and "/>
            </xpath>
            <xpath expr="//button[@name='action_invoice_sent'][not(hasclass('oe_highlight'))]" position="attributes">
                <attribute name="invisible" add="state != 'posted' or not is_being_sent and not invoice_pdf_report_id or not can_send_as_self_invoice" separator=" and "/>
            </xpath>
        </data>