title: Parse JSON date in Flutter
body: <p>An API response I should use in my Flutter app contains date in JSON in a format like this:  /Date(1559985189000+0300)/</p>
  
  <p>When parsing I have the following exception:
  FormatException (FormatException: Invalid date format
  /Date(1559985189000+0300)/)</p>
  
  <p>I use this code to parse: <code>date: DateTime.parse(json["Date"])</code></p>
  
  <p>Date string seems an unix timestamp to me.</p>
  
  <p>Is there a built in way to parse this date string to DateTime in Flutter, or should I implement it?</p>
  
  <p>Thanks a lot! </p>