@Nullable private String getFirstNormal(String name) {
        for (int i = 0; i < size(); i++) {
            if (name(i).equals(name)) {
                return value(i);
            }
        }
        return null;
    }
Get the first value found for this key even if there are multiple. If none, then
return the specified defaultValue.
zuul-core/src/main/java/com/netflix/zuul/message/Headers.java