private Set<String> keysToSet(final String keys) {
        if (NullSafe.isBlankString(keys)) {
            return Collections.emptySet();
        } else {
            return NullSafe.stream(keys.split(META_KEYS_DELIMITER))
                    .filter(Objects::nonNull)
                    .filter(Predicate.not(String::isBlank))
                    .map(String::trim)
                    .map(String::toLowerCase)
                    .collect(Collectors.toSet());
        }
    }
Handler class that forwards the request to a URL.
stroom-pipeline/src/main/java/stroom/pipeline/writer/HTTPAppender.java