Sorting Json struct from vibe.d - json

Question

I faced a problem with wrong sorting JSON keys. I use mongo db and I need to send a creating user form command.
vibe-d JSON:
Json a2 = Json([
"createUser": Json(req.form["user"]),
"pwd": Json(req.form["password"]),
"roles": Json([
Json([
"role": Json(req.form["access"]),
"db": Json("3dstore")
])
])
]);
logInfo(a2.toString());
Output:
[main(Wbp2) INF] {"roles":[{"role":"readWrite","db":"3dstore"}],"createUser":"111","pwd":"1"}
std.json:
JSONValue a2 = JSONValue([
"createUser": JSONValue(req.form["user"]),
"pwd": JSONValue(req.form["password"]),
"roles": JSONValue([
JSONValue([
"role": JSONValue(req.form["access"]),
"db": JSONValue("3dstore")
])
])
]);
logInfo(a2.toString());
Output:
[main(vVOX) INF] {"createUser":"111","pwd":"1","roles":[{"db":"3dstore","role":"readWrite"}]}
Therefore I get an error in mongo output:
"errmsg" : "no such command: 'roles'"
Any ideas?