in src/Google.Cloud.Functions.Framework/GcfEvents/GcfConverters.cs [471:480]
protected override void PopulateAttributes(Request request, CloudEvent evt)
{
// Source is as normal
base.PopulateAttributes(request, evt);
// Obtain the subject from the data if possible.
if (request.Data.TryGetValue("uid", out var uid) && uid is JsonElement uidElement && uidElement.ValueKind == JsonValueKind.String)
{
evt.Subject = $"users/{uidElement.GetString()}";
}
}