docs: private void visitActionFieldList(ActionInsertFact afl) {
          String factType = afl.getFactType();
          for (ActionFieldValue afv : afl.getFieldValues()) {
              InterpolationVariable var = new InterpolationVariable(afv.getValue(),
                                                                    afv.getType(),
                                                                    factType,
                                                                    afv.getField());
              if (afv.getNature() == FieldNatureType.TYPE_TEMPLATE && !vars.containsKey(var)) {
                  vars.put(var,
                           vars.size());
              }
          }
      }