@Override public int compare(TraceIdTimestamp left, TraceIdTimestamp right) {
        long x = left.timestamp, y = right.timestamp;
        int result = Long.compare(x, y); // Long.compareTo is JRE 7+
        if (result != 0) return -result; // use negative as we are descending
        return right.lowTraceId.compareTo(left.lowTraceId);
      }
Used for testing. Returns all dependency links unconditionally.
zipkin/src/main/java/zipkin2/storage/InMemoryStorage.java