class HttpHeadersGetter implements TextMapGetter<MultiValueMap<String, String>> {
    public static final HttpHeadersGetter INSTANCE = new HttpHeadersGetter();


    @Override
    public Iterable<String> keys(MultiValueMap<String, String> map) {
        return map.keySet();
    }

    @Nullable
    @Override
    public String get(@Nullable MultiValueMap<String, String> map, String key) {<FILL_FUNCTION_BODY>}
}

        if (map == null) {
            return null;
        }
        List<String> code = map.get(key);

        return CollectionUtils.isEmpty(code) ? null : code.get(code.size() - 1);
    
<no_super_class>