title: Flutter plugin development Unresolved reference: io
body: <p>Its my first attempt to create a flutter plugin, I created flutter plugin project from android studio and its running fine, when I tried to add platform specific code for android I stuck in some issues, in the same project platform specific code editing is almost dead (no linting).
  I imported MyPluginProject/android in android studio and there are also some issues, </p>
  
  <pre><code>Unresolved reference: io
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/NHhAp.png" rel="noreferrer"><img src="https://i.stack.imgur.com/NHhAp.png" alt="enter image description here"></a></p>
  
  <p>Here is output of <code>flutter doctor</code></p>
  
  <pre><code>Doctor summary (to see all details, run flutter doctor -v):
  [✓] Flutter (Channel stable, v1.7.8+hotfix.2, on Linux, locale en_US.UTF-8)
  
  [✓] Android toolchain - develop for Android devices (Android SDK version 29.0.0)
  [✓] Android Studio (version 3.4)
  [✓] Connected device (1 available)
  
  • No issues found!
  </code></pre>