How to add to an ember blueprint's renamedFiles property?

An ember blueprint has a static property called renamedFiles that by default renames gitignore from the files folder to .gitignore in the target folder.

The question is, how can I extend this list?

So far I tried these in the index.js of my blueprint, but they don't seem to work:

module.exports = {

  renamedFiles: {
    'something': 'somethingElse'
  },

  beforeInstall: function() {
    this._super.renamedFiles = {
      'something': 'somethingElse',
    };
  }
};