@Override
        public void sleep(Duration duration) {
            try {
                Thread.sleep(duration.toMillis());
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new RuntimeException(e);
            }
        }
An abstraction used for mocking {@link Thread#sleep(long)} in unit tests.

@author bjorncs
http-utils/src/main/java/ai/vespa/util/http/hc4/retry/Sleeper.java