code: public boolean checkExistingExpression(
      String topicExpression,
      boolean isWildcarded)
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
          SibTr.entry(
            tc,
            "checkExistingExpression",
            new Object[] {topicExpression, new Boolean(isWildcarded)});
      boolean alreadyRegistered = false;
  
      if(isWildcarded)
      {
        if(_registeredWildcardConsumerMonitors.containsKey(topicExpression))
          alreadyRegistered = true;
      }
      else
      {
        if(_registeredExactConsumerMonitors.containsKey(topicExpression))
          alreadyRegistered = true;
      }
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "checkExistingExpression", new Boolean(alreadyRegistered));
  
      return alreadyRegistered;
    }
docs: Method checkExistingExpression
  
  This method determines whether the ConsumerMonitorRegistrar has already
  registered callbacks on a specified topicExpresson.
  
  @param topicExpression
  @param isWildcarded
  @return