`build_runner` fails when flutter formatter breaks lines after long class names

[mastermakrela]

In packages/brick_build/lib/src/builders/model_dictionary_builder.dart:67, the code uses a simple string match to find class declarations:

entry.value.contains('class ${annotation.element.name} ')

This fails when Flutter's formatter formats long class declarations and breaks the line after the class name: Example that fails:

// Before formatting (works)
class VeryLongClassNameThatExceedsTheEightyCharacterLimit extends SomeBaseClass {
  // ...
}
// After formatting (fails)
class VeryLongClassNameThatExceedsTheEightyCharacterLimit
    extends SomeBaseClass {
  // ...
}

The space after the class name is replaced with a newline, causing the contains check to fail and the build to break with an error like: StateError: Bad state: No element

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It's not a critical issue, when one knows it's there, nevertheless it's annoying in codebase which uses formatter, linter and build_runner.