code: public Collection<String> predictSeveral(@NonNull LabelledDocument document, int limit) {
          if (document.getReferencedContent() != null) {
              return predictSeveral(document.getReferencedContent(), limit);
          } else
              return predictSeveral(document.getContent(), limit);
      }
docs: Predict several labels based on the document.
  Computes a similarity wrt the mean of the
  representation of words in the document
  @param document raw text of the document
  @return possible labels in descending order