private static String render(final SpanData spanData) {
    return new ToStringBuilder(spanData, ToStringStyle.NO_CLASS_NAME_STYLE)
      .append("spanId", spanData.getSpanId()).append("name", spanData.getName())
      .append("hasEnded", spanData.hasEnded()).toString();
  }
A Rudimentary tool for visualizing a hierarchy of spans. Given a collection of spans, indexes
them from parents to children and prints them out one per line, indented.
hbase-client/src/test/java/org/apache/hadoop/hbase/client/trace/StringTraceRenderer.java