XML:Lang Support

When multiple documentation tags with xml:lang
are present, only one of them should be rendered.

Example Schema

<?xml
    version = '1.0'
    encoding = 'UTF-8'
?>

<xs:schema xmlns:xs = 'http://www.w3.org/2001/XMLSchema' >

    <xs:element
        name = 'dummy'
        type = 'xs:string'
    >

        <xs:annotation>

            <xs:documentation xml:lang = 'en' >

               English

            </xs:documentation>

            <xs:documentation xml:lang = 'jp' >

                Japanese

            </xs:documentation>

        </xs:annotation>

    </xs:element>

</xs:schema>

Currently

The content from all documentation tags is concatenated.

Desired

Only the contents of one of the documentation tags is rendered.

Order

I'd suggest the following order:

• If possible render doc tag with lang fitting the user
• If possible fall back on a setting for default xml lang
• If possible fall back on the first doc tag without lang
• Fall back on the first doc tag

Reproduce the issue with the supplied XML schema and confirm that multiple xs:documentation tags are concatenated. Trace the XML documentation rendering entry point and determine how user language and default xml:lang settings are exposed; done means one tag is selected using the requested fallback order.