PromiseKit 6, Alamofire, Xcode 10.2/Swift 5

Question

I'm having trouble writing the following code:

    public
    func
    get(organization inSID: String)
        -> Promise<Organization>
    {
        URLSession.showNetworkActivity()
        return firstly
        {
            let req = buildRequest(path: "/api/\(inUUID)", date: inDate, headers: [.organizationSID : inSID])
            self.mgr.request(req).responseJSON()
        }
        .map()
        { inData, inResp in
            return Organization(sid: "")
        }
        .ensure
        {
            URLSession.hideNetworkActivity()
        }
    }

I get an error on firstly: Ambiguous reference to member 'firstly(execute:)'

After adding import PMKAlamofire to the top of my file, and being more explicit, I get this to compile:

    public
    func
    get(organization inSID: String)
        -> Promise<Organization>
    {
        URLSession.showNetworkActivity()
        return firstly
        { () -> Promise<(json: Any, response: PMKAlamofireDataResponse)> in
            let req = buildRequest(path: "/api/v2/organizations/\(inSID)", headers: [.organizationSID : inSID])
            return self.mgr.request(req).responseJSON()
        }
        .map()
        { inResp in
            return Organization(sid: "")
        }
        .ensure
        {
            URLSession.hideNetworkActivity()
        }
    }

Note the added explicit () -> Promise<(json: Any, response: PMKAlamofireDataResponse)> and the explicit return statement in the firstly closure. I don't know if this is now required by Swift 5 or it still can't properly infer types.