magento-test/app/code/Magento/MediaContentSynchronizationCms/etc/di.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:ObjectManager/etc/config.xsd">
    <type name="Magento\MediaContentSynchronizationApi\Model\SynchronizerPool">
        <arguments>
            <argument name="synchronizers" xsi:type="array">
                <item name="media_content_block_synchronizer" xsi:type="object">Magento\MediaContentSynchronizationCms\Model\Synchronizer\Block</item>
                <item name="media_content_page_synchronizer" xsi:type="object">Magento\MediaContentSynchronizationCms\Model\Synchronizer\Page</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\MediaContentSynchronizationApi\Model\SynchronizeIdentitiesPool">
        <arguments>
            <argument name="synchronizers" xsi:type="array">
                <item name="media_content_cms"
                      xsi:type="object">Magento\MediaContentSynchronizationCms\Model\Synchronizer\SynchronizeIdentities
                </item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\MediaContentSynchronizationApi\Model\GetEntitiesInterface">
        <arguments>
            <argument name="entities" xsi:type="array">
                <item name="cms_block" xsi:type="string">Magento\Cms\Api\Data\BlockInterface</item>
                <item name="cms_page" xsi:type="string">Magento\Cms\Api\Data\PageInterface</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\MediaContentSynchronizationCms\Model\Synchronizer\Block">
        <arguments>
            <argument name="fields" xsi:type="array">
                <item name="content" xsi:type="string">content</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\MediaContentSynchronizationCms\Model\Synchronizer\Page">
        <arguments>
            <argument name="fields" xsi:type="array">
                <item name="content" xsi:type="string">content</item>
            </argument>
        </arguments>
    </type>
</config>