Unexpected values of queryParams on a controller using decorators

[jonopus]

I'm seeing unexpected values of queryParams on a controller using decorators.

Steps to reproduce:

1. Add the following init method to tests/dummy/app/controllers/index.js.

init(){
  this._super(...arguments);
  console.log(this.get('queryParams'));
}

2. Serve the app
   #. Notice in the console that queryParams is an array of hashes rather than an array or a hash.

[
  {"parachuteOpen":{"as":"parachute"}},
  {"parachuteOpen":{"as":"parachute"},"page":{"as":"page"}},
  {"parachuteOpen":{"as":"parachute"},"page":{"as":"page"},"search":{"as":"search"}},
  {"parachuteOpen":{"as":"parachute"},"page":{"as":"page"},"search":{"as":"search"},"tags":{"as":"tags"}}
]

I would have expected this value to be in one of the following formats:
[ "parachuteOpen", "page", "search", "tags" ]
{"parachuteOpen":{"as":"parachute"},"page":{"as":"page"},"search":{"as":"search"},"tags":{"as":"tags"}}

I believe this is cause when each decorator adds an additional init call.
One possible solution might be to guard against calling init multiple times.