code: public static String getTopic(final Map<String, Object> stormConfig) {
          if (stormConfig.containsKey(CONFIG_TOPIC)) {
              // get configured topic from config as string, removing whitespace from both ends
              final String topic = String.valueOf(stormConfig.get(CONFIG_TOPIC)).trim();
              if (topic.length() > 0) {
                  return topic;
              }
              else {
                  LOG.warn("configured topic found in storm config is empty, defaulting to topic '{}'", DEFAULT_TOPIC);
                  return DEFAULT_TOPIC;
              }
          }
          else {
              LOG.warn("no configured topic found in storm config, defaulting to topic '{}'", DEFAULT_TOPIC);
              return DEFAULT_TOPIC;
          }
      }
docs: Retrieves the topic to be consumed from storm's configuration map, or the {@link #DEFAULT_TOPIC} if no
  (non-empty) value was found using {@link #CONFIG_TOPIC}.
  
  @param stormConfig Storm's configuration map.
  @return The topic to be consumed.