Function next_delay 

pub(super) fn next_delay(
    prev: Option<Duration>,
    opts: &ReconnectOptions,
    rng: &mut XorShift32,
) -> Duration

Computes the next reconnect delay from the previous one.

None yields the initial delay. Otherwise the previous delay is grown by the multiplier, capped at max_delay, and reduced by random jitter. The BackoffMultiplier (finite, >= 1.0) and Jitter (0.0..=1.0) newtypes guarantee the inputs are in range, so the result is always a non-negative, finite duration and this never has to be defensive.