How to point to multiple catalogs via schema.org

itemlist.jsonld

{
  "@id": "http://foo.org/id/doc/1",
  "@context": "https://schema.org/",
  "@type": "ItemList",
  "url": "http://en.wikipedia.org/wiki/Billboard_200",
  "name": "Top music artists",
  "description": "The artists with most cumulative weeks at number one according to Billboard 200",
  "itemListElement": [
    {
      "@id": "http://foo.org/id/doc/1/li1",
      "@type": "ListItem",
      "position": 1,
      "item": {
         "@id": "http://foo.org/id/doc/1/li1/dc1",
        "@type": "DataCatalog",
        "name": "dc1",
        "url" : "http://opencoredata.org/dc/1"
      }
    },
    {
      "@id": "http://foo.org/id/doc/1/li2",
      "@type": "ListItem",
      "position": 2,
      "item": {
         "@id": "http://foo.org/id/doc/1/li1/dc2",
        "@type": "DataCatalog",
        "name": "dc2",
        "url" : "http://opencoredata.org/dc/2"
      }
    }
  ]
}