code: public void track(String event, Properties properties) {
      if (isNullOrEmpty(event)) {
        throw new IllegalArgumentException("event must not be null or empty.");
      }
  
      if (properties == null) {
        properties = new Properties();
      }
  
      dispatcher.dispatchPayload(
          new WearPayload(BasePayload.Type.track, new WearTrackPayload(event, properties)));
    }
docs: The track method is how you record any actions your users perform. Each action is known by a
  name, like 'Purchased a T-Shirt'. You can also record properties specific to those actions. For
  example a 'Purchased a Shirt' event might have properties like revenue or size.
  
  @param event Name of the event. Must not be null or empty.
  @param properties {@link Properties} to add extra information to this call
  @throws IllegalArgumentException if event name is null or an empty string
  @see <a href="https://segment.com/docs/tracking-api/track/">Track Documentation</a>
  @see com.segment.analytics.Analytics#track(String, Properties)