default CompletableFuture<String> convert(RestRequest restRequest, String input) {
    CompletableFuture<String> future = new CompletableFuture<>();
    convert(restRequest, input, CallbackUtils.fromCompletableFuture(future));
    return future;
  }
Converts an ID.
@param restRequest {@link RestRequest} representing the request.
@param input the ID that needs to be converted.
@return a {@link CompletableFuture} that will eventually contain the converted ID.
ambry-api/src/main/java/com/github/ambry/frontend/IdConverter.java