docs: public RetryPolicy<R> withJitter(Duration jitter) {
      Assert.notNull(jitter, "jitter");
      Assert.isTrue(jitter.toNanos() > 0, "jitter must be > 0");
      Assert.state(delay != null || delayMin != null, "A delay must be configured");
      Assert.state(jitterFactor == 0.0, "withJitter(double) has already been called");
      Assert.state(jitter.toNanos() <= delay.toNanos(), "jitter must be less than the configured delay");
      this.jitter = jitter;
      return this;
    }