curl --request POST \
  --url https://sandbox.api.app.firstsales.io/api/v1/organizations/{orgId}/workspaces/{wsId}/campaigns/{campaignId}/launch/prepare \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "savedVersionId": "<string>",
  "readinessVersion": "<string>",
  "testOverride": true
}
'

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({savedVersionId: '<string>', readinessVersion: '<string>', testOverride: true})
};

fetch('https://sandbox.api.app.firstsales.io/api/v1/organizations/{orgId}/workspaces/{wsId}/campaigns/{campaignId}/launch/prepare', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{}

{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "requestId": "<string>",
    "details": {}
  }
}