code: public ExpiryPolicyBuilder<K, V> update(Duration update) {
      if (update != null && update.isNegative()) {
        throw new IllegalArgumentException("Update duration must be positive");
      }
      return update((a, b, c) -> update);
    }
docs: Set TTL since last update.
  <p>
  Note: Calling this method on a builder with an existing TTL since last access will override the previous value or function.
  
  @param update TTL since last update
  @return a new builder with the TTL since last update