List<Span> spansByTraceId(String lowTraceId) {
    List<Span> sameTraceId = new ArrayList<>();
    for (TraceIdTimestamp traceIdTimestamp : traceIdToTraceIdTimestamps.get(lowTraceId)) {
      sameTraceId.addAll(spansByTraceIdTimestamp.get(traceIdTimestamp));
    }
    return sameTraceId;
  }
Returns service names orphaned by removing the trace ID
zipkin/src/main/java/zipkin2/storage/InMemoryStorage.java