Multisite TYPO3 V9, Distinct Robots.txt For Multiple Domains On One Rootpage

For marketing purposes do I maintain one identical website with two different domains, in TYPO3 v8 I would simply add a domain record on the root page and create a personalised robots.txt with typoscript for each site trough realurl) ...

With v9 I cannot find a way to do this, I tried to enter various anottations in config.yaml manually, but nothing works (i.e. I tried to replicate the annotation for the url)...

routes:
  -
    route: robots.txt
    type: staticText
    content: "User-agent: *\r\nDisallow: /"
    contentVariants:
      -
        content: "User-agent: *\r\nAllow: /"
        condition: 'getenv("HTTP_HOST") == "2dn-domain.com"'

does anyone know a working annotation, or a different approach ...

I like to stay within the 'regular' solutions so I found a middleground:

in the backend you enter a Route Type = Page, File or URL [uri]

with value t3://page?type=201 so as to address a page type for robots

and with Typoscript you define your conditional robots file:

# Theme robots.txt

robots = PAGE
robots {
    typeNum = 201
    config {
        disableAllHeaderCode = 1
        additionalHeaders.10.header = Content-Type:text/plain;charset=utf-8
        xhtml_cleaning = 0
        admPanel = 0
        debug = 0
        index_enable = 0
        removeDefaultJS = 1
        removeDefaultCss = 1
        removePageCss = 1
        INTincScript_ext.pagerender = 1
        sourceopt.enabled = 0
    }

    10 = TEXT
    10.value (
User-Agent: *
Allow: /

# indexed search
User-agent: googlebot
Disallow: /*?tx_indexedsearch

# folders
Disallow: /typo3/
Disallow: /typo3conf/
Allow: /typo3conf/ext/
Allow: /typo3temp/

# parameters
Disallow: /*?id=*                    # non speaking URLs
Disallow: /*&id=*                    # non speaking URLs
Disallow: /*cHash                    # no cHash
Disallow: /*tx_powermail_pi1         # no powermail thanks pages
Disallow: /*tx_form_formframework    # no forms

# sitemap
Sitemap: {$theme.configuration.sitemap}
    )
}

# Adwords Site closed
[globalString = ENV:HTTP_HOST=adw-domain.com]
    robots.10.value (
User-Agent: *
Disallow: /
    )
[global]

I also set a constant in constants.typoscript for the seo site:

theme.configuration {
    sitemap = /?eID=dd_googlesitemap
    sitemap = http://seo-domain.com/sitemap/seo-domain.xml
}