code: public boolean hasSpanWithId(String id) {
          TraceState ts = traceState.get();
  
          if (id != null && ts != null) {
              boolean spanFound = ts.getSpanForId(id) != null;
              if (log.isLoggable(Level.FINEST)) {
                  log.finest("Has span with id = " + id + "? " + spanFound);
              }
              return spanFound;
          }
  
          return false;
      }
docs: This method determines whether there is a span available
  associated with the supplied id.
  
  @return Whether a span exists with the id