I use the nuxeo bootstrap to create a new polymer project :

nuxeo bootstrap polymer
cd *-web
mvn package

But when I access my application in my browser, I have a 404 error on the service-worker.js file.

I added this file in polymer.json :

  "extraDependencies": [
    "manifest.json",
    "bower_components/webcomponentsjs/webcomponents-lite.min.js",
    "service-worker.js"
  ],

And now It's ok. My environment :

Nuxeo CLI             : 1.8.2
Modules
 - generator-nuxeo    : 2.8.0 
 - yeoman-environment : 2.0.5