code: public RestApiResponse execute(long timeout, TimeUnit timeUnit) {
          return Blocking.blockForSingle(delegate.execute(), timeout, timeUnit);
      }
docs: Executes the API request in a synchronous fashion, using the given timeout.
  
  @param timeout the custom timeout to use for the request.
  @param timeUnit the {@link TimeUnit} for the timeout.
  @return the result of the API call, as a {@link RestApiResponse}.
  @throws RuntimeException wrapping a {@link TimeoutException} in case the request took too long.