The suppression was wired as a finalizedBy task on generateSafeArgs, which only orders it after generation, not before the Kotlin compile that consumes the generated sources. The two then race, and under strict-serial scheduling the compile reliably wins and fails the generated NavGraphDirections under -Werror. Fold the rewrite into each generateSafeArgs task's own final action so the output is clean before the task completes. Differential Revision: https://phabricator.services.mozilla.com/D306513