public GracefulShutdown build() {
        validateGreaterThanOrEqual(timeout, "timeout", quietPeriod, "quietPeriod");
        return new DefaultGracefulShutdown(quietPeriod, timeout, toException);
    }
Builds a new {@link GracefulShutdown} with the configured parameters.
core/src/main/java/com/linecorp/armeria/server/GracefulShutdownBuilder.java