public Communication convertToConcrete() {
    if (comm != null) return comm;
    AnalyticUUIDGeneratorFactory f = new AnalyticUUIDGeneratorFactory();
    AnalyticUUIDGenerator g = f.create();
    comm = new Communication();
    comm.setId(id);
    comm.setUuid(g.next());
    comm.setType(communicationType);
    comm.setMetadata(Conll2011.META_GENERAL);

    // Tokenization for the words
    // TokenTagging for the POS tags
    // Parse for the constituency parse
    // TokenTagging for NER labels
    String sectionNum = null;
    Section section = null;
    for (Conll2011Sentence sent : sentences) {
      if (sectionNum == null || !sent.getPart().equals(sectionNum)) {
        if (section != null) comm.addToSectionList(section);
        section = new Section();
        section.setUuid(g.next());
        section.setKind(Conll2011.SECTION_TYPE);
        sectionNum = sent.getPart();
      }
      section.addToSentenceList(sent.convertToConcrete(g));
    }
    assert section != null;
    comm.addToSectionList(section);

    //  SituationMentionSet for the SRL labels
    propBankSrlSituationMentions = new SituationMentionSet();
    propBankSrlSituationMentions.setUuid(g.next());
    propBankSrlSituationMentions.setMetadata(Conll2011.META_SRL);
    propBankSrlSituationMentions.setMentionList(new ArrayList<>());
    for (Conll2011Sentence s : sentences) {
      for (int pai = 0; pai < s.getNumPredicates(); pai++) {
        SituationMention sm = s.getPredArg(pai, g);
        assert sm.getTokens() != null || sm.getConstituent() != null;
        propBankSrlSituationMentions.addToMentionList(sm);
      }
    }
    comm.addToSituationMentionSetList(propBankSrlSituationMentions);

    // EntitySet and EntityMentionSet for the coref labels
    addCoref(comm);

    // EntityMentionSet for the NER labels
    if (this.conll2011.addNerAsEntityMentionSet) {
      nerEms = new EntityMentionSet();
      nerEms.setUuid(g.next());
      nerEms.setMetadata(Conll2011.META_NER);
      nerEms.setMentionList(new ArrayList<>());
      for (Conll2011Sentence s : sentences)
        for (EntityMention em : s.getNerEntityMentions()) nerEms.addToMentionList(em);
      comm.addToEntityMentionSetList(nerEms);
    }

    return comm;
  }