private void addRoot(TypeMigrationUsageInfo info, PsiType migrationType) {
    final HashSet<TypeMigrationUsageInfo> parents = new HashSet<>();
    parents.add(info);
    final MigrationNode migrationNode =
        new MigrationNode(getProject(), info, migrationType, myLabeler, parents, new HashMap<>());

    myCachedChildren.add(migrationNode);
  }
private void addRoot(TypeMigrationUsageInfo info, PsiType migrationType)