Generate Robust C# Code

从 C# 代码片段生成入口开始，将当前的 form-urlencoded 输出与 issue 中的两个示例进行比较，重点关注参数名称和值的表示方式。完成的标准是：生成的 C# 使用带有运行时安全 URL 编码的请求参数，而不是嵌入一个经过编码的请求体字符串。

Improvement Suggestion:

I would have liked the following autogenerated C# for a HTTP POST request with the single parameter err of value + & serialized as x-www-form-urlencoded in the body.

var client = new RestClient("https://localhost");
var request = new RestRequest(Method.POST);
request.AddHeader("postman-token", "da4d0044-61a9-3943-40db-9e753aca6020");
request.AddHeader("cache-control", "no-cache");
Action<string,string> parameter = (name, value) => request.AddParameter(name, value);
parameter("err", "+ &");
IRestResponse response = client.Execute(request);

but what Postman did produce for me was the following C# code:

var client = new RestClient("https://localhost");
var request = new RestRequest(Method.POST);
request.AddHeader("postman-token", "da4d0044-61a9-3943-40db-9e753aca6020");
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("application/x-www-form-urlencoded", "err=%2B%20%26", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

Rationale

1. parameter("err", "+ &"); is more readable than "[..] err=%2B%20%26 [..]". The value, + &, is more recognizable.
2. The code is more maintanable. At work, I tried the following development workflow:
   (a) Type a minimal working example request into to Postman.
   (b) Generate C# code.
   (c) Copy generated code to Visual Studio.
   (d) Replace example values by C# method parameters.
   This workflow failed, because the method parameters were not x-www-form-urlencoded at runtime. Generating UrlEncode() calls would make writing a consumer of a HTTP POST x-www-form-urlencoded API effortless.
3. This usage of IRestRequest.AddParameter is encouraged, whereas the currently generated code depends on an internal hack not meant for 3rd party usage.
   /// - RequestBody: Used by AddBody() (not recommended to use directly)

App Details:

Postman for Windows
Version 5.3.2
win32 6.1.7601 / x64

Continuation of: https://github.com/postmanlabs/postman-app-support/issues/3870