docs: private static Map<Variable, Type> getLabelVarTypeMap(TransactionOLTP tx, Set<Fragment> allFragments) {
          Map<Variable, Type> labelVarTypeMap = new HashMap<>();
          allFragments.stream()
                  .filter(LabelFragment.class::isInstance)
                  .forEach(fragment -> {
                      // TODO: labels() should return ONE label instead of a set
                      SchemaConcept schemaConcept = tx.getSchemaConcept(
                              Iterators.getOnlyElement(((LabelFragment) fragment).labels().iterator()));
                      if (schemaConcept != null && !schemaConcept.isRole() && !schemaConcept.isRule()) {
                          labelVarTypeMap.put(fragment.start(), schemaConcept.asType());
                      }
                  });
          return labelVarTypeMap;
      }