class CommunityMatchExprVarCollector implements CommunityMatchExprVisitor<Set<CommunityVar>, Configuration> {

  @Override
  public Set<CommunityVar> visitCommunityAcl(CommunityAcl communityAcl, Configuration arg) {
    return visitAll(
        communityAcl.getLines().stream()
            .map(CommunityAclLine::getCommunityMatchExpr)
            .collect(ImmutableList.toImmutableList()),
        arg);
  }

}