widget.xml

<?xml version="1.0" encoding="UTF-8"?>
<widgets xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Widget:etc/widget.xsd">
    <widget id="example_widget_with_ui_components"
            class="Grasch\AdminUi\Block\Widget\ExampleOfUIComponents">
        <label translate="true">Example Of Widget With Ui Components</label>
        <description translate="true">Example Of Widget With Ui Components</description>
        <parameters>
            <parameter name="component_data" xsi:type="block">
                <block class="Grasch\AdminUi\Block\Adminhtml\Widget\Ui\Components">
                    <data>
                        <item name="namespace" xsi:type="string">widget_example_form</item>
                    </data>
                </block>
            </parameter>
        </parameters>
    </widget>
</widgets>