code: public void resume(String id) {
          try {
              suspendedStateLock.lock();
  
              TraceState ts = suspendedState.get(id);
  
              if (ts != null) {
                  clearExpire(ts);
  
                  // Log after finding trace state, otherwise may generate alot of logging
                  if (log.isLoggable(Level.FINEST)) {
                      log.finest("Resume trace state = " + ts + " id = " + id);
                  }
  
                  // Check if thread already used
                  if (traceState.get() != null && log.isLoggable(Level.FINEST)) {
                      log.finest("WARNING: Overwriting previous trace state = " + traceState.get());
                  }
  
                  traceState.set(ts);
  
                  suspendedState.remove(id);
              }
          } finally {
              suspendedStateLock.unlock();
          }
      }
docs: This method attempts to resume a previously suspended trace state
  associated with the supplied id. When resumed, the trace state is
  associated with the current thread.
  
  @param id The id of the trace state to resume