private Set<String> getMetaKeySet(final String csv) {
        if (NullSafe.isEmptyString(csv)) {
            return Collections.emptySet();
        } else {
            // Use LinkedHashSet to preserve order
            return Arrays.stream(csv.split(","))
                    .map(String::trim)
                    .filter(NullSafe::isNonBlankString)
                    .map(String::toLowerCase)
                    .collect(Collectors.toCollection(LinkedHashSet::new));
        }
    }
Handler class that forwards the request to a URL.
stroom-pipeline/src/main/java/stroom/pipeline/writer/HTTPAppender.java