Android:如何使用Retrofit在所有url的末尾添加内容？

public class CustomConverterFactory extends Converter.Factory {
    @Override
    public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) {
        return new Converter<ResponseBody, Object>() {
            @Override
            public Object convert(ResponseBody value) throws IOException {
                // 处理响应的转换
                return value.string();
            }
        };
    }

    @Override
    public Converter<?, RequestBody> requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
        return new Converter<Object, RequestBody>() {
            @Override
            public RequestBody convert(Object value) throws IOException {
                // 处理请求的转换
                RequestBody requestBody = RequestBody.create(MediaType.parse("application/json"), value.toString());
                // 在URL末尾添加内容
                String newUrl = retrofit.baseUrl().toString() + "/extra";
                return RequestBody.create(requestBody.contentType(), requestBody.contentLength(), newUrl);
            }
        };
    }
}

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl("http://example.com")
        .addConverterFactory(new CustomConverterFactory())
        .build();