class DefaultHttpRequestMessage implements HttpRequestMessage {

    //消息体
    private ByteBuf payload;

    private String url;

    //请求方法
    private HttpMethod method;

    //请求头
    private List<Header> headers = new ArrayList<>();

    //参数
    private Map<String, String> queryParameters = new HashMap<>();

    //请求类型
    private MediaType contentType;

    private MultiPart multiPart;

    @Override
    public Optional<MultiPart> multiPart() {
        return Optional
            .ofNullable(multiPart)
            .filter(part -> part.getParts().size() > 0);
    }

    public void setBody(Object body) {<FILL_FUNCTION_BODY>}

    @Override
    public String toString() {
        return print();
    }
}

        if (body instanceof ByteBuf) {
            setPayload(((ByteBuf) body));
        } else if (body instanceof String) {
            setPayload(Unpooled.wrappedBuffer(((String) body).getBytes()));
        } else if (body instanceof byte[]) {
            setPayload(Unpooled.wrappedBuffer(((byte[]) body)));
        } else if (MediaType.APPLICATION_JSON.includes(getContentType())) {
            setPayload(Unpooled.wrappedBuffer(JSON.toJSONBytes(body)));
        } else if (MediaType.APPLICATION_FORM_URLENCODED.includes(getContentType()) && body instanceof Map) {
            setPayload(Unpooled.wrappedBuffer(HttpUtils.createEncodedUrlParams(((Map<?, ?>) body)).getBytes()));
        } else if (body != null) {
            setPayload(Unpooled.wrappedBuffer(JSON.toJSONBytes(body)));
        } else {
            setPayload(Unpooled.EMPTY_BUFFER);
        }
    
<no_super_class>