public void add(HeaderName headerName, String value) {
        String normalName = Objects.requireNonNull(headerName, "headerName").getNormalised();
        Objects.requireNonNull(value, "value");
        addNormal(headerName.getName(), normalName, value);
    }
Adds the name and value to the headers.
zuul-core/src/main/java/com/netflix/zuul/message/Headers.java