private Integer readTimeout(Element spec) {
        String timeout = spec.getAttribute("timeout");

        return (timeout.isEmpty())?
                null :
                TimeParser.asMilliSeconds(timeout);
    }
Builds federation options from a federations options element
@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/chains/search/FederationOptionsBuilder.java