public long getGracefulShutdownTimeoutMillis() {
        return gracefulShutdownTimeoutMillis;
    }
Returns the number of milliseconds to wait before shutting down the server regardless of active requests.

@see #getGracefulShutdownQuietPeriodMillis()
@see ServerBuilder#gracefulShutdownTimeout(Duration, Duration)
spring/boot3-autoconfigure/src/main/java/com/linecorp/armeria/spring/ArmeriaSettings.java