title: Non-public API usage Flutter.framework/Flutter: _kCTFontOpticalSizeAttribute error on upload of flutter app
body: <p>I've spent the last two days trying to submit my app to the App Store. I get the message below:</p>
  
  <pre><code>ITMS-90338: Non-public API usage - The app references non-public symbols in Frameworks/Flutter.framework/Flutter: _kCTFontOpticalSizeAttribute. If method names in your source code match the private Apple APIs listed above, altering your method names will help prevent this app from being flagged in future submissions. In addition, note that one or more of the above APIs may be located in a static library that was included with your app. If so, they must be removed. For further information, visit the Technical Support Information at http://developer.apple.com/support/technical/
  </code></pre>
  
  <p>Here's what Ive done so far:</p>
  
  <p>a) I've scoured my code for any reference to Font Sizes - I had some that were constants - I changed the constant name to:</p>
  
  <pre><code> k_fontSizeMyName
  </code></pre>
  
  <p>b) I tried to download the latest flutter sdk version
  c) I rebuilt my entire keychain.</p>
  
  <p>Im so desperate right now. im tired.
  What do I do?</p>
  
  <p>the internet has no mention of this bug.</p>