private void findChildren(List<Span> spans, Span parentSpan, List<Span> childrenSpan) {
        spans.forEach(span -> {
            if (span.getSegmentParentSpanId().equals(parentSpan.getSegmentSpanId())) {
                childrenSpan.add(span);
                findChildren(spans, span, childrenSpan);
            }
        });
    }
@param duration nullable unless for BanyanDB query from cold stage
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/TraceQueryService.java