title: C# How to create a generic List of KeyValuePair
body: <p>I have created a list of KeyValuePair to populate the content as the data for the HttpClient. </p>
  
  <pre><code>List&lt;KeyValuePair&lt;string, string&gt;&gt; keyValues = new List&lt;KeyValuePair&lt;string, string&gt;&gt;();
  
  keyValues.Add(new KeyValuePair&lt;string, string&gt;("email", email));
  keyValues.Add(new KeyValuePair&lt;string, string&gt;("password", password));
  keyValues.Add(new KeyValuePair&lt;string, string&gt;("plan_id", planId));
  
  var content = new FormUrlEncodedContent(keyValues);
  </code></pre>
  
  <p>But later I found I have to send a int value as the plan_id. How can change the above list to accept KeyValuePair. Or is there any better way to do this?</p>