title: What Promoted Object should I use when creating an AdSet with lead_generation optimization goal?
body: <p>I'm using facebookads python api, v2.6.</p>
  
  <p>I'm trying to create an AdSet with optimization goal = lead_generation.</p>
  
  <p>This is my code:</p>
  
  <pre><code>ad_set = AdSet(parent_id = 'act_%s' % FB_ACCOUNT)
  ad_set[AdSet.Field.name]= 'Teste AdSet'
  ad_set[AdSet.Field.campaign_id]='6043402838999'
  ad_set[AdSet.Field.status]=AdSet.Status.paused
  ad_set[AdSet.Field.billing_event] = AdSet.BillingEvent.impressions
  ad_set[AdSet.Field.optimization_goal] = AdSet.OptimizationGoal.lead_generation
  ad_set[AdSet.Field.daily_budget]= 100
  ad_set[AdSet.Field.bid_amount]= 1
  ad_set[AdSet.Field.start_time]= '2016-07-01'
  ad_set[AdSet.Field.promoted_object]= 
  ad_set[AdSet.Field.targeting]= {Targeting.Field.geo_locations: { 'countries': ['BR']},Targeting.Field.genders: [1],Targeting.Field.age_min: 20,Targeting.Field.age_max: 24}
  
  ad_set.remote_create()
  </code></pre>
  
  <p>But when I run this I get this error:</p>
  
  <pre><code> Status:  400
    Response:
      {
        "error": {
          "code": 100,
          "is_transient": false,
          "error_subcode": 1885024,
          "error_user_msg": "When creating an ad set within a campaign using the Body of an error/warning message. Title is: Promoted Object Missing objective, a promoted object must be specified.",
          "error_user_title": "Promoted Object Missing",
          "message": "Invalid parameter",
          "type": "OAuthException",
          "fbtrace_id": "B9hyZlpzS7O"
        }
      }
  </code></pre>
  
  <p>I tried to find any documentation about this, but could not. On the official docs I don't see LEAD_GENERATION on the promoted objects options:</p>
  
  <p><a href="https://developers.facebook.com/docs/marketing-api/reference/ad-campaign#Creating" rel="nofollow">https://developers.facebook.com/docs/marketing-api/reference/ad-campaign#Creating</a></p>
  
  <p>Anyone had this problem?</p>