magento-test/app/code/Magento/Swatches/etc/adminhtml/events.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="product_attribute_form_build_main_tab">
        <observer name="add_swatch_fields_to_attribute" instance="Magento\Swatches\Observer\AddFieldsToAttributeObserver" />
    </event>
    <event name="adminhtml_product_attribute_types">
        <observer name="swatch_attribute_type" instance="Magento\Swatches\Observer\AddSwatchAttributeTypeObserver" />
    </event>
</config>