function _findMatchingGlob(pathData, filename) {
        var globs = Object.keys(pathData),
            globCounter;

        if (!filename) {
            return;
        }

        for (globCounter = 0; globCounter < globs.length; globCounter++) {
            var glob = globs[globCounter];

            if (globmatch(filename, glob)) {
                return glob;
            }
        }
    }
@private

Look for a matching file glob among the collection of paths.

@param {Object} pathData The keys are globs and the values are the preferences for that glob
@param {string} filename relative filename to match against the globs
@return {?string} glob pattern that matched, if any