code: public final void cancelRequest(long tick)
    {
      Long objTick = Long.valueOf(tick);
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(tc, "cancelRequest", objTick);
  
      ArrayList<AORequestedTick> satisfiedTicks = null;
      
      try
      {
        this.lock();
        try
        {
          // it is possible that this event occurs after this object is closed.
          // it is safe to ignore it since we must have already transitioned the tick to its final state
          if (closed)
          {
            if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(tc, "cancelRequest");
    
            return;
          }
          AORequestedTick requestedTick =
            (AORequestedTick) tableOfRequests.get(objTick);
          
          if (requestedTick != null)
          {
            boolean transitionOccured = cancelRequestInternal(requestedTick, false);
          
            // If we expired the request and have more then process those
            // requests now
            if (transitionOccured && !listOfRequests.isEmpty())
              satisfiedTicks = processQueuedMsgs(null);
          }
    
        }
        finally
        {
          this.unlock();
        }
      }
      catch(SINotPossibleInCurrentConfigurationException e)
      {
        // No FFDC code needed
        notifyException(e);
      }
      
      if (satisfiedTicks != null)
      {
        // inform parent about satisfied ticks - outside lock
        int length = satisfiedTicks.size();
        for (int i = 0; i < length; i++)
        {
          AORequestedTick aotick = (AORequestedTick) satisfiedTicks.get(i);
          parent.satisfiedRequest(aotick.tick, aotick.getMessage());
        }
      }
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "cancelRequest");
    }
docs: This method is called by the parent to cancel a request. Note that it is possible that the
  request has already been satisfied, and parent.satisfiedRequest() is being called concurrently
  with this method.
  @param tick The tick identifying the request