Jaeger headers forwarding with Isito does not work

app_one.js

'use strict';

const express = require('express');

// Constants
const PORT = 8080;
const HOST = '0.0.0.0';

// App
const app = express();
app.get('/', (req, res) => {
    var s = "headers: ";
    var h = req.headers;
    for(var key in h) {
        s += key + ": " + h[key] + "\n";
    }
  res.send('app_one.v2: Hello world\n\n' + s);
});

app.listen(PORT, HOST);
console.log(`Running app_one on http://${HOST}:${PORT}`);

app_two.js

'use strict';

const express = require('express');
const request = require('request');

// Constants
const PORT = 8081;
const HOST = '0.0.0.0';

// App
const app = express();

function as_string(o) {
    return JSON.stringify(o, null, '  ');
}

app.get('/2/echo', (req, res) => {,
    var opts = {
        "url": "http://app-one-svc:8080/",
        "headers" : {
            "x-b3-traceid": req.headers["x-b3-traceid"],
            "x-b3-spanid" : req.headers["x-b3-spanid"],
            "x-b3-sampled": req.headers["x-b3-sampled"],
            "x-request-id": req.headers["x-request-id"]
        }
    };

    request(opts, function(err, rs, body) {
        var s = as_string(req.headers)
        + "\nBACKEND:\n"
        + "\n\tERR: " + err
        + "\n\tRES: " + as_string(rs)
        + "\n\tBDY: " + body
        + "\n\topts: " + as_string(opts);
        res.send('app_two.v2: Echoing from backend...\n\n' + s);
    });
});

app.listen(PORT, HOST);
console.log(`Running app_two on http://${HOST}:${PORT}`);

output.txt

app_two.v2: Echoing from backend...

{
  "host": "192.168.99.106:31380",
  "user-agent": "curl/7.54.0",
  "accept": "*/*",
  "x-forwarded-for": "172.17.0.1",
  "x-forwarded-proto": "http",
  "x-envoy-internal": "true",
  "x-request-id": "4833e88b-ec7a-928a-931a-0c4a2ff96c9e",
  "x-envoy-decorator-operation": "app-two-svc.default.svc.cluster.local:8081/2/echo",
  "x-b3-traceid": "25ec6c82faefc749",
  "x-b3-spanid": "25ec6c82faefc749",
  "x-b3-sampled": "1",
  "x-istio-attributes": "Ck8KCnNvdXJjZS51aWQSQRI/a3ViZXJuZXRlczovL2lzdGlvLWluZ3Jlc3NnYXRld2F5LTdmZjhkOGI1NTctNThibGQuaXN0aW8tc3lzdGVtCj4KE2Rlc3RpbmF0aW9uLnNlcnZpY2USJxIlYXBwLXR3by1zdmMuZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbApBChdkZXN0aW5hdGlvbi5zZXJ2aWNlLnVpZBImEiRpc3RpbzovL2RlZmF1bHQvc2VydmljZXMvYXBwLXR3by1zdmMKQwoYZGVzdGluYXRpb24uc2VydmljZS5ob3N0EicSJWFwcC10d28tc3ZjLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAopChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSDRILYXBwLXR3by1zdmM=",
  "content-length": "0"
}
BACKEND:

	ERR: null
	RES: {
  "statusCode": 200,
  "body": "app_one.v2: Hello world\n\nheaders: x-b3-traceid: 25ec6c82faefc749\nx-b3-spanid: 25ec6c82faefc749\nx-b3-sampled: 1\nx-request-id: 4833e88b-ec7a-928a-931a-0c4a2ff96c9e\nhost: app-one-svc:8080\nconnection: close\n",
  "headers": {
    "x-powered-by": "Express",
    "content-type": "text/html; charset=utf-8",
    "content-length": "203",
    "etag": "W/\"cb-F/Kyvo0Pde3nbBfUVn3w/8lmTR0\"",
    "date": "Sat, 16 Mar 2019 05:54:54 GMT",
    "connection": "close"
  },
  "request": {
    "uri": {
      "protocol": "http:",
      "slashes": true,
      "auth": null,
      "host": "app-one-svc:8080",
      "port": "8080",
      "hostname": "app-one-svc",
      "hash": null,
      "search": null,
      "query": null,
      "pathname": "/",
      "path": "/",
      "href": "http://app-one-svc:8080/"
    },
    "method": "GET",
    "headers": {
      "x-b3-traceid": "25ec6c82faefc749",
      "x-b3-spanid": "25ec6c82faefc749",
      "x-b3-sampled": "1",
      "x-request-id": "4833e88b-ec7a-928a-931a-0c4a2ff96c9e"
    }
  }
}
	BDY: app_one.v2: Hello world

headers: x-b3-traceid: 25ec6c82faefc749
x-b3-spanid: 25ec6c82faefc749
x-b3-sampled: 1
x-request-id: 4833e88b-ec7a-928a-931a-0c4a2ff96c9e
host: app-one-svc:8080
connection: close

	opts: {
  "url": "http://app-one-svc:8080/",
  "headers": {
    "x-b3-traceid": "25ec6c82faefc749",
    "x-b3-spanid": "25ec6c82faefc749",
    "x-b3-sampled": "1",
    "x-request-id": "4833e88b-ec7a-928a-931a-0c4a2ff96c9e"
  }
}

I'm calling app-two-svc: curl http://192.168.99.106:31380/2/echo .. which calls app-one-svc.