private void addAttributeIfHeaderDefined(final AttributeMap attributeMap, final String headerText) {
        if (headerText == null || headerText.length() < 3) {
            return;
        }
        if (!headerText.contains(":")) {
            throw new IllegalArgumentException("Additional Headers must be specified as 'Name: Value', but '"
                                               + headerText + "' supplied.");
        }

        int delimiterPos = headerText.indexOf(':');
        attributeMap.put(headerText.substring(0, delimiterPos), headerText.substring(delimiterPos + 1));
        LOGGER.debug("Added '{}' to {}", headerText, attributeMap);
    }
Handler class that forwards the request to a URL.
stroom-pipeline/src/main/java/stroom/pipeline/writer/HTTPAppender.java