code: public void suspend(String id) {
          TraceState ts = traceState.get();
  
          if (log.isLoggable(Level.FINEST)) {
              log.finest("Suspend trace state = " + ts + " id = " + id);
          }
  
          if (ts != null) {
              setExpire(ts);
  
              try {
                  suspendedStateLock.lock();
  
                  // Check if id already used
                  if (suspendedState.containsKey(id) && log.isLoggable(Level.FINEST)) {
                      log.finest("WARNING: Overwriting previous suspended trace state = " + suspendedState.get(id)
                              + " id = " + id);
                  }
  
                  suspendedState.put(id, ts);
  
                  traceState.remove();
              } finally {
                  suspendedStateLock.unlock();
              }
          }
      }
docs: This method suspends any current trace state, associated with
  this thread, and associates it with the supplied id. This
  state can then be re-activated using the resume method.
  
  @param id The id to associated with the suspended trace state