<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
<extension_attributes for="Magento\Sales\Api\Data\OrderInterface">
    <attribute code="text_attribute" type="string"/>
</extension_attributes>
<extension_attributes for="Magento\Sales\Api\Data\OrderItemInterface">
    <attribute code="design_id" type="string" />
</extension_attributes>
</config>