public AbstractRequestContextBuilder requestStartTime(long requestStartTimeNanos,
                                                          long requestStartTimeMicros) {
        this.requestStartTimeNanos = requestStartTimeNanos;
        this.requestStartTimeMicros = requestStartTimeMicros;
        requestStartTimeSet = true;
        return this;
    }
Sets the request start time of the request.

@param requestStartTimeNanos the {@link System#nanoTime()} value when the request started.
@param requestStartTimeMicros the number of microseconds since the epoch when the request started.
core/src/main/java/com/linecorp/armeria/common/AbstractRequestContextBuilder.java