I'm trying to integrate mercury payment gateway to 'website' module. While creating a data file, I am getting an error of extra element but I did as it's done in base code and I took reference of PayPal integration. 
here is my code,

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
    <record id="payment_acquirer_mercury" model="payment.acquirer">
        <field name="name">Mercury</field>
        <field name="image" type="base64" file="payment_mercury/static/src/img/mercury_icon.png"/>
        <field name="provider">mercury</field>
        <field name="company_id" ref="base.main_company"/>
        <field name="view_template_id" ref="mercury_acquirer_button"/>
        <field name="environment">test</field>
        <field name="pre_msg"><![CDATA[
<p>You will be redirected to the Mercury website after clicking on the payment button.</p>]]></field>
        <field name="mercury_merchant_id">dummy</field>
        <field name="mercury_password" password="True">dummy</field>
    </record>
</odoo>