Forward slash in JSON key treated as error

[jakubklimek]

A forward slash in JSON key like this:

{
  "@context": {
    "@version": 1.1,
    "a/b": "https://a"
  }
}

is treated as bad syntax: jsonld.SyntaxError: Invalid JSON-LD syntax; term in form of IRI must expand to definition.
However, forward slash is perfectly valid in JSON.
Where does this syntax error come from?

{
  "@context": {
    "@version": 1.1,
    "a_b": "https://a"
  }
}

is OK.

[jakubklimek]

However, Apache Jena riot also reports this as invalid:

ERROR org.apache.jena.riot - A local context contains a term that has an invalid or missing IRI mapping [code=INVALID_IRI_MAPPING].

when used like this:

{
  "@context": {
    "@version": 1.1,
    "a/b": "https://a"
  },
  "@id": "https://id",
  "a/b": 2
}

[lemoustachiste]

@jakubklimek your issue is not too far from the one I was having here: #542. Maybe it can help