Execute the HTTP request.

HttpMigration.execute() is a function executing the HTTP request to the HTTP server.

It returns the response body from the API endpoint when the status code is 200 or 201. Otherwise, it throws an HttpError when the status code is not 200 or 201.

If you want to get more information than the response body, or get the detailed response information even when the status code is 200 or 201, use the HttpMigration.propagate function instead.

HttpError when the API endpoint responds none 200/201 status.