code: public static String getLemmaLemmaKey(Term term1, Term term2) {
  		List<String> lemmas = new ArrayList<>(2);
  		lemmas.add(term1.getWords().get(0).getWord().getLemma());
  		lemmas.add(term2.getWords().get(0).getWord().getLemma());
  		Collections.sort(lemmas);
  		return String.format("%s+%s", lemmas.get(0), lemmas.get(1));
  	}
docs: Return the term pair indexing key that is compliant with {@link TermValueProviders#ALLCOMP_PAIRS}.
  
  @see TermValueProviders#ALLCOMP_PAIRS
  @param term1
  First term of the pair
  @param term2
  Second term of the pair
  @return
  The indexing key for the given pair