@Override
    public String builder(final String paramName, final ServerWebExchange exchange) {
        List<String> headers = exchange.getRequest().getHeaders().get(paramName);
        if (CollectionUtils.isEmpty(headers)) {
            return "";
        } 
        return headers.get(0);
    }
@Test
    public void testBuilder() {
        assertEquals("", parameterData.builder("invalidParamName", exchange));
        assertEquals("shenyuHeader", parameterData.builder("shenyu", exchange));
    }