core/src/main/java/com/digitalpebble/stormcrawler/Metadata.java
public static String getFirstValue(Metadata md, String... keys) {
        for (String key : keys) {
            String val = md.getFirstValue(key);
            if (StringUtils.isBlank(val))
                continue;
            return val;
        }
        return null;
    }
public static String getFirstValue(Metadata md, String... keys) {
        for (String key : keys) {
            String val = md.getFirstValue(key);
            if (StringUtils.isBlank(val))
                continue;
            return val;
        }
        return null;
    }
Returns the first non empty value found for the keys or null if none
found.