code: public CircuitBreaker<R> withDelay(Duration delay) {
      Assert.notNull(delay, "delay");
      Assert.isTrue(delay.toNanos() >= 0, "delay must not be negative");
      this.delay = delay;
      return this;
    }
docs: Sets the {@code delay} to wait in open state before transitioning to half-open.
  
  @throws NullPointerException if {@code delay} is null
  @throws IllegalArgumentException if {@code delay} < 0