private void closeAll(List<NamedReader> readers) {
        for (NamedReader reader : readers) {
            try { reader.close(); } catch (IOException e) { }
        }
    }
Reads all query profile xml files in a given directory,
and all type xml files from the immediate subdirectory "types/" (if any)

@throws IllegalArgumentException if the directory is not readable, or if there is some error in the XML
container-search/src/main/java/com/yahoo/search/query/profile/config/QueryProfileXMLReader.java