Why is an XML node not matshing my yaml (adds a s)

For the API at https://app.swaggerhub.com/apis/Windward-Studios/windward-rest_ful_api/2.0#free

If you look at the XML (not JSON) for POST v2/document, inside it it has

<Datasets>

    <Datasets>

        <Name>string</Name>

        <Query>string</Query>

    </Datasets>

</Datasets>

The inner <Datasets> should be <Dataset>. Why is it making it plural?

thanks - dave