Updates a variant. Only the fields you send are changed, with one exception: changing language to a different language or project template clears the variant's starter files, since code written for one environment does not fit another. The variant then opens with the new language's default code or the project template's own files. To keep starter code, send contents or file_contents in the same request. The solution is kept.

file_contents replaces all of the variant's files. An empty array resets a project template variant to the template's own files.