Is it possible to add a CTA to a single image ad through Marketing API?

Hi all,

I'm using the marketing API and was trying to create a single image ad. I was able to add everything to match the campaign manager fields except for call to action. I looked everywhere and can't find a reference to adding a call to action for a share in the share api so i can then use when creating the ad creative. I'm assuming it is possible because the campaign manager UI allows the user to do it, and since I'm able to match everything else I figured a CTA was possible too.

I used the structure below to create a share using the share api (to use as reference in the creative), I believe the property for CTA might be needed here somewhere. I tried adding it directly into where I create an Ad Creative referencing the share, but it seems CTAs there are only possible when creating Ad Gen creatives.

 {
      content: {
        contentEntities: [
          {
            entityLocation: {{destinationUrl}},
            thumbnails: [
              {
                resolvedUrl: {{url}},
              },
            ],
          },
        ],
        title: {{headline}},
        shareMediaCategory: 'ARTICLE',
      },
      distribution: {
        'linkedInDistributionTarget': {},
      },
      owner: {{urn:li:organization:#######}},
      agent: {{urn:li:sponsoredAccount:####}}
      subject: {{adName}}
      text: {
        text: {{introText}}
      },
  };

I make a post and hit https://api.linkedin.com/v2/shares

Any help would be greatly appreciated.

Thanks in advance!