title: Flutter hive: cannot generate Adapter files
body: <p>I have a model like so:</p>
  <pre><code>import 'package:uuid/uuid.dart';
  import 'package:hive/hive.dart';
  
  part 'config_item.g.dart';
  
  @HiveType()
  class ConfigItem {
    @HiveField(0)
    String _id; // this can be a uuid or a MongoDB ObjectID
    @HiveField(1)
    final String deviceName;
  ....
  }
  </code></pre>
  <p>I like to generate the Adapter file but it <strong>does not want to do it</strong>! When I call <code>flutter packages pub run build_runner build  --delete-conflicting-outputs</code> I get the following output:</p>
  <pre><code>flutter packages pub run build_runner build  --delete-conflicting-outputs                main  ✭ ✈
  [INFO] Generating build script...
  [INFO] Generating build script completed, took 399ms
  
  [SEVERE] Nothing can be built, yet a build was requested.
  [INFO] Initializing inputs
  [INFO] Reading cached asset graph...
  [INFO] Reading cached asset graph completed, took 45ms
  
  [INFO] Checking for updates since last build...
  [INFO] Checking for updates since last build completed, took 399ms
  
  [INFO] Running build...
  [INFO] Running build completed, took 3ms
  
  [INFO] Caching finalized dependency graph...
  [INFO] Caching finalized dependency graph completed, took 35ms
  
  [INFO] Succeeded after 53ms with 0 outputs (0 actions)
  </code></pre>
  <p>In my <code>pubspec.yaml</code> I have:</p>
  <pre><code>environment:
    sdk: &quot;&gt;=2.12.0 &lt;3.0.0&quot;
  
  dependencies:
    flutter:
      sdk: flutter
  
  
    # The following adds the Cupertino Icons font to your application.
    # Use with the CupertinoIcons class for iOS style icons.
    cupertino_icons: ^1.0.2
    bottom_navy_bar: ^6.0.0
    get_it: ^7.2.0
    get_it_mixin: ^3.1.3
    servicestack: ^2.0.0
    font_awesome_flutter: ^9.1.0
    hive: ^2.0.4
    hive_flutter: ^1.1.0
    path_provider: ^2.0.3
    uuid: ^3.0.4
  
  dev_dependencies:
    flutter_test:
      sdk: flutter
    build_runner:
  </code></pre>
  <p>I tried all sort of things like</p>
  <ul>
  <li>Delete .dart_tool folder</li>
  <li>Adding <code>*.g.dart</code> to <code>.gitignore</code></li>
  <li><code>flutter clean</code></li>
  <li>and a lot more I found when searching the net.</li>
  </ul>
  <p><strong>But nothing helps!</strong> Any idea what is missing?</p>
  <p>I am using the latest (stable) versions of flutter, dart SDK and AndroidStudio.</p>