It is the white space. How to remove this white space in first row?
<dynamicRows name="attribute_options_select" >
<settings>
<addButtonLabel translate="true">Add Value</addButtonLabel>
<additionalClasses>
<class name="admin__field-wide">true</class>
</additionalClasses>
<componentType>dynamicRows</componentType>
</settings>
<container name="record" component="Magento_Ui/js/dynamic-rows/record">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="isTemplate" xsi:type="boolean">true</item>
<item name="is_collection" xsi:type="boolean">true</item>
<item name="componentType" xsi:type="string">container</item>
</item>
</argument>
<field name="is_default" component="OX_CustomerAttributes/js/form/element/checkbox" sortOrder="0"
formElement="checkbox">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="prefixElementName" xsi:type="string">option_</item>
<item name="inputCheckBoxName" xsi:type="string">default.</item>
<item name="columnsHeaderClasses" xsi:type="string">control-table-options-th</item>
<item name="modules" xsi:type="array">
<item name="rows" xsi:type="string">ns = ${ $.ns }, index = attribute_options_select
</item>
</item>
</item>
</argument>
<settings>
<additionalClasses>
<class name="control-table-options-cell">true</class>
</additionalClasses>
<dataType>boolean</dataType>
<label translate="true">Is Default</label>
</settings>
<formElements>
<checkbox>
<settings>
<prefer>radio</prefer>
</settings>
</checkbox>
</formElements>
</field>
<field name="position" component="OX_CustomerAttributes/js/form/element/input" formElement="input">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="prefixName" xsi:type="string">option.order</item>
<item name="prefixElementName" xsi:type="string">option_</item>
</item>
</argument>
<settings>
<dataType>text</dataType>
<visible>false</visible>
</settings>
</field>
</container>
</dynamicRows>