Annotations are not properly rendered in JavaDoc when using <pre>{@code}

```

{@code

{@literal @}Override

}

```

Produces
```

{ @}Override

```

Instead of:
```

@Override

```

Imported from Jira [BEAM-1295](https://issues.apache.org/jira/browse/BEAM-1295). Original Jira may contain additional context.
Reported by: staslev.

Reproduce the JavaDoc example from the issue and compare the rendered output with the expected @Override text. Then trace the JavaDoc rendering path responsible for

{@code} and {@literal @}; done means the annotation renders without the extra braces and the regression is covered by an appropriate test.

Written by the indexing model from the issue text.