default long requestDurationNanos() {
        return requestEndTimeNanos() - requestStartTimeNanos();
    }
Returns the duration that was taken to consume or produce the request completely, in nanoseconds.

@throws RequestLogAvailabilityException if the property is not available yet.
@see RequestLogProperty#REQUEST_END_TIME
core/src/main/java/com/linecorp/armeria/common/logging/RequestOnlyLog.java