contract/contract_show_invoice/views/contract_view.xml

<?xml version="1.0"?>
<odoo>

    <record id="act_analytic_invoices" model="ir.actions.act_window">
        <field name="context">{'search_default_analytic_account_ids':
            [active_id], 'default_analytic_account_ids': active_id}</field>
        <field name="name">Invoices</field>
        <field name="res_model">account.invoice</field>
        <field name="domain">[('analytic_account_ids','=',active_id)]</field>
        <field name="search_view_id" ref="account.view_account_invoice_filter" />
    </record>

    <record id="action_contract_show_invoice_tree" model="ir.actions.act_window.view">
        <field name="sequence" eval="1"/>
        <field name="view_mode">tree</field>
        <field name="view_id" ref="account.invoice_tree"/>
        <field name="act_window_id" ref="act_analytic_invoices"/>
    </record>

    <record id="action_contract_show_invoice_form" model="ir.actions.act_window.view">
        <field name="sequence" eval="2"/>
        <field name="view_mode">form</field>
        <field name="view_id" ref="account.invoice_form"/>
        <field name="act_window_id" ref="act_analytic_invoices"/>
    </record>

    <record id="account_analytic_account_button_invoice" model="ir.ui.view">
        <field name="name">account.analytic.account.button.invoice
        </field>
        <field name="model">account.analytic.account</field>
        <field name="inherit_id" ref="analytic.view_account_analytic_account_form" />
        <field name="arch" type="xml">
            <xpath expr='//div[@name="button_box"]' position='inside'>
                <button class="oe_stat_button" type="action" icon="fa-edit"
                    name="%(contract_show_invoice.act_analytic_invoices)d"
                    string="Invoices" help="Invoices related with this contract">
                </button>
            </xpath>
        </field>
    </record>

</odoo>