getting blank marathon ui, how to get authorization working?

[f1-outsourcing]

I am starting marathon with /etc/default/marathon and MESOSPHERE_HTTP_CREDENTIALS=bla:testpassword

this is my marathon plugin.conf

{
  "plugins": {
    "capabilities": {
      "plugin": "mesosphere.marathon.plugin.task.RunSpecTaskProcessor",
      "implementation": "com.criteo.marathon.CapabilitiesPlugin"
    },
    "authorization": {
      "plugin": "mesosphere.marathon.plugin.auth.Authorizer",
      "implementation": "mesosphere.marathon.example.plugin.javaauth.JavaAuthorizer",
      "configuration": {
        "users": [
          {
            "user": "bla",
            "permissions": [
              { "allowed": "create", "on": "/" },
              { "allowed": "update", "on": "/" },
              { "allowed": "delete", "on": "/" },
              { "allowed": "view", "on": "/" }
            ]
          }
        ]
      }
    }
  }
}