private static Map<String, List<String>> parseFormParameters(String formContent) {
        if (formContent.isEmpty()) {
            return Map.of();
        }

        Map<String, List<String>> parameterMap = new HashMap<>();
        String[] params = formContent.split("&");
        for (String param : params) {
            String[] parts = param.split("=");
            String paramName = urlDecode(parts[0]);
            String paramValue = parts.length > 1 ? urlDecode(parts[1]) : "";
            List<String> currentValues = parameterMap.get(paramName);
            if (currentValues == null) {
                currentValues = new LinkedList<>();
                parameterMap.put(paramName, currentValues);
            }
            currentValues.add(paramValue);
        }
        return parameterMap;
    }
Parses application/x-www-form-urlencoded data into a map of parameters.

@param formContent raw form content data (body)
@return map of decoded parameters
container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/FormPostRequestHandler.java