Why can't I add keywords to my adGroup it says newKeywordBuilder is not a function of adGroup

[Dan Savage]

This script will add an ad group to my campaign but will not add the keywords or ads.

It gives me an error of 

newKeywordBuilder is not a function of adGroup. 

I'm following the documentation so not sure what is going on. It does successful add the adgroup to the campaign but then gives the error.

function main() {

  // Specify the campaign name where you want to upload the ads
  var campaignName = ' myCampaign 1';

  // Specify the CPC bid in cents (11 cents in this case)
  var cpcBidInDollars = .05;

  // Array of ad data containing headlines, descriptions, and URLs
  var adData = [{
"headlines": [
"Headline1",
"Headline2",
"Headline3",
"Headline4"
],
"descriptions": [
"descr 1.",
"descr 2"
],
"finalUrl": "https://website.com",
"keywords": [
"keywords phrase"
]
}
  ];
 




  // Create ads from the ad data array
 var campaign = AdsApp.campaigns().withCondition("Name = '" + campaignName + "'").get().next();

  // Create adgroup from the ad data array
  for (var i = 0; i < adData.length; i++) {
    var adGroup = campaign.newAdGroupBuilder()
      .withName('Ad Group ' + (i))

       .withCpc(.05)

  .build();

 
  var keywordOperation = adGroup.newKeywordBuilder()
   .withText(adData[i].keywords[0])
   .withCpc(.05)
   .build();
   

    var adOperation = adGroup.newAd().responsiveSearchAdBuilder()
  .withHeadlines(adData[i].headlines)
  .withDescriptions(adData[i].descriptions)
  .withFinalUrl("https://treatmentminer.com")
  .build();
  }

}