the sample request which I tried was somthing like this :

{
  "sourceDefinitionId": "69589781-7828-43c5-9f63-8925b1c1ccc2",
  "connectionConfiguration": {
    "s3_endpoint": "",
    "access_key_id": "xxxx",
    "s3_bucket_name": "abcd",
    "s3_bucket_path": "raw",
    "s3_bucket_region": "region",
    "secret_access_key": "xxxx"
  },
  "workspaceId": "7a2f3b32-a061-4e9d-a42e-75c879d1c7db",
  "name": "S3-API-TEST"
}