JSONLD and base URL

[Erich Bremer]

I'm trying to use a "@id": "./" in a jsonld file and in another triple
"@id": "picture.jpg".  The "./" will be correctly changed to the base URL,
but the "@id": "picture.jpg" just gets dropped and a blank node is
created.  Below is the code segment that I used to generate this output:
{
    "@context": [
        "http://schema.org";
    ],
    "@graph": [
        {
            "@type": "CreativeWork",
            "@id": "picture.jpg"
        },
        {
            "@id": "./",
            "@type": "DataSet"
        }
    ]
}
_:Bd42dbcf4e4ffb76e199766bf5e4c1e4b <
http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <
http://schema.org/CreativeWork> .
<http://mydomain.com> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <
http://schema.org/DataSet> .

If I use https://json-ld.org/playground/ on the same jsonld, I get:

<https://json-ld.org/playground/> <
http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/DataSet>
.
<https://json-ld.org/playground/picture.jpg> <
http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <
http://schema.org/CreativeWork> .

which is what I expected.  Am I missing something here?  - Erich

    String json = "{\n" +
"    \"@context\": [\n" +
"        \"http://schema.org\"\n"; +
"    ],\n" +
"    \"@graph\": [\n" +
"        {\n" +
"            \"@type\": \"CreativeWork\",\n" +
"            \"@id\": \"picture.jpg\"\n" +
"        },\n" +
"        {\n" +
"            \"@id\": \"./\",\n" +
"            \"@type\": \"DataSet\"\n" +
"        }\n" +
"    ]\n" +
"}";
    System.out.println(json);
    Model m = ModelFactory.createDefaultModel();
    InputStream inputStream = new
ByteArrayInputStream(json.getBytes(Charset.forName("UTF-8")));
    RDFParser.create()
        .base("http://mydomain.com";)
        .source(inputStream)
        .lang(RDFLanguages.JSONLD)
        .parse(m);
    RDFDataMgr.write(System.out, m, RDFFormat.NQUADS) ;