code: protected Set<String> getAvailableStreamIds() {
      HashSet<String> ids = new HashSet<String>();
      ids.add(getStreamId());
      return ids;
    }
docs: Get the available stream ids in the Streamlet. For most Streamlets,
  there is only one internal stream id, therefore the function
  returns a set of one single stream id.
  @return Returns a set of one single stream id.