code: public synchronized Topic getTopic(String topicName) {
          if (topicName == null || topicName.length() == 0) {
              throw new JavametricsException("Topic names must not be null or 0 length");
          }
          if (topics.containsKey(topicName)) {
              return topics.get(topicName);
          } else {
              Topic topic = new TopicImpl(topicName);
              topics.put(topicName, topic);
              return topic;
          }
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.javametrics.Javametrics#getTopic(java.lang.String)