docs: function userInfo (options) {
    var self = this
    options = options || {}
    var uri = self.configuration.userinfo_endpoint
    var agentOptions = self.agentOptions
  
    if (!options.token) {
      return Promise.reject(new Error('Missing access token'))
    }
    var requestOptions = {
      url: uri,
      method: 'GET',
      headers: {
        'Authorization': 'Bearer ' + options.token
      },
      json: true,
      agentOptions: agentOptions
    }
  
    if (self.proxy) {
      requestOptions.proxy = self.proxy
    }
    // Access token is present
    return Promise.resolve()
      .then(function () {
        // return a request promise
        return request(requestOptions)
      })
  }