title: Flutter/Dart Uri not escaping colon ":" in URL
body: <p>The following uri created:</p>
  
  <pre><code>final _url = "https://example.com/api/";
  final _uri = Uri(path: _url, queryParameters: _params);
  </code></pre>
  
  <p>Results in <code>http%3A//example.com/api/+{params...}</code></p>
  
  <p>I have tried escaping by <code>\:</code> and other methods but no luck :/</p>
  
  <p>This problem only happens when run through Uri, I was unable to find any resources online to resolve this issue.</p>