void makePackageDoc(PackageSymbol pack, String docComment, JCCompilationUnit tree) {
        PackageDocImpl result = packageMap.get(pack);
        if (result != null) {
            if (docComment != null) result.setRawCommentText(docComment);
            if (tree != null) result.setTree(tree);
        } else {
            result = new PackageDocImpl(this, pack, docComment, tree);
            packageMap.put(pack, result);
        }
    }