code: private String buildSendTopicExpression(
      String destName,
      String discriminator)
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(
          tc,
          "buildSendTopicExpression",
          new Object[] { destName, discriminator });
  
      String combo = null;
  
      if (discriminator == null || discriminator.trim().length() == 0)
        combo = destName;
      else
        combo =
          destName
            + MatchSpace.SUBTOPIC_SEPARATOR_CHAR
            + discriminator;
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "buildSendTopicExpression", combo);
  
      return combo;
    }
docs: Concatenates topicspace and a topic expression with a level separator between
  
  Null or empty topics are treated as topics at the root level so the
  combination topic becomes topicSpace/
  
  @param topicSpace  The topicspace name
  @param discriminator  The topic