example.jsonld

{
	"@context": {
		"foo": {
			"@id": "http://example.com/foo",
			"@container": "@set"
		}
	},
	"foo": [
		{
			"@context": {"foo": "http://example.com/other"},
			"foo": 42
		}
	]
}

nested.jsonld

{
	"@context": {
		"foo": {
			"@context": {"foo": "http://example.com/other"},
			"@id": "http://example.com/foo",
			"@container": "@set"
		}
	},
	"foo": [
		{"foo": 42}
	]
}