public Map<String, String> filterAttributes(final AttributeMap attributeMap) {
        // Use a LinkedHashMap to adhere to metaKeySet order, which is a LinkedHashSet
        if (NullSafe.hasItems(metaKeySet)) {
            final Map<String, String> map = new LinkedHashMap<>(metaKeySet.size());
            metaKeySet.forEach(key ->
                    map.put(key, attributeMap.get(key)));
            return map;
        } else {
            return Collections.emptyMap();
        }
    }
Handler class that forwards the request to a URL.
stroom-pipeline/src/main/java/stroom/pipeline/writer/HTTPAppender.java