PrivilegeVector DocumentSourceUnionWith::LiteParsed::requiredPrivileges(
    bool isMongos, bool bypassDocumentValidation) const {
    PrivilegeVector requiredPrivileges;
    invariant(_pipelines.size() <= 1);
    invariant(_foreignNss);

    // If no pipeline is specified, then assume that we're reading directly from the collection.
    // Otherwise check whether the pipeline starts with an "initial source" indicating that we don't
    // require the "find" privilege.
    if (_pipelines.empty() || !_pipelines[0].startsWithInitialSource()) {
        Privilege::addPrivilegeToPrivilegeVector(
            &requiredPrivileges,
            Privilege(ResourcePattern::forExactNamespace(*_foreignNss), ActionType::find));
    }

    // Add the sub-pipeline privileges, if one was specified.
    if (!_pipelines.empty()) {
        const LiteParsedPipeline& pipeline = _pipelines[0];
        Privilege::addPrivilegesToPrivilegeVector(
            &requiredPrivileges,
            std::move(pipeline.requiredPrivileges(isMongos, bypassDocumentValidation)));
    }
    return requiredPrivileges;
}