private void CreateImmutableMaps() { if (lazyImmutableWikiEntrySourcePathMap == null && lazyImmutableWikiEntryWikiUrlMap == null) { // create immutable map from source map ImmutableMapCreationVisitor visitor = new ImmutableMapCreationVisitor(); rootDirectory.Accept(visitor); lazyImmutableWikiEntrySourcePathMap = visitor.CreateFinalSourcePathMap(); lazyImmutableWikiEntryWikiUrlMap = visitor.CreateFinalWikiUrlMap(); } }