title: firebase cloud function won't store cookie named other than "__session"
body: <p>i followed the sample of <a href="https://github.com/firebase/functions-samples/tree/master/authorized-https-endpoint" rel="noreferrer">authorized-https-endpoint</a> and only added console.log to print the req.cookies, the problem is the cookies are always empty <code>{}</code> I set the cookies using client JS calls and they do save but from some reason, I can't get them on the server side.</p>
  
  <p>here is the full code of index.js, it's exactly the same as the sample:</p>
  
  <pre><code>'use strict';
  
  const functions = require('firebase-functions');
  const admin = require('firebase-admin');
  admin.initializeApp(functions.config().firebase);
  const express = require('express');
  const cookieParser = require('cookie-parser')();
  const cors = require('cors')({origin: true});
  const app = express();
  
  const validateFirebaseIdToken = (req, res, next) =&gt; {
    console.log(req.cookies); //// &lt;----- issue this is empty {} why?? 
    next();
  };
  
  app.use(cors);
  app.use(cookieParser);
  app.use(validateFirebaseIdToken);
  app.get('/hello', (req, res) =&gt; {
    res.send(`Hello!!`);
  });
  
  exports.app = functions.https.onRequest(app);
  </code></pre>
  
  <p>store cookie:</p>
  
  <p><code>curl http://FUNCTION_URL/hello --cookie "__session=bar" // req.cookies =
   {__session: bar}</code></p>
  
  <p>doesn't store:</p>
  
  <p><code>curl http://FUNCTION_URL/hello --cookie "foo=bar" // req.cookies =
   {}</code></p>