etc/email_templates.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Email:etc/email_templates.xsd">
<template id="abandoned_template" label="Abandoned" file="abandoned.html" type="html" module="UOL_PagSeguro" area="frontend"/>
</config>