private void calculateDurationExcludeChild(ProfileStackElement element) {
        element.setDurationChildExcluded(element.getDuration() - children.stream().mapToInt(t -> t.duration).sum());
    }
calculate duration to {@link ProfileStackElement#getDurationChildExcluded()}, expends on {@link
#calculateDuration(ProfileStackElement)}
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/profiling/trace/analyze/ProfileStackNode.java