[sproctor]

Description

preMerge has been red on nucleus-3.0 since the Flathub work landed, which fails the gradle job on every PR and skips the jobs behind it (test-packaging, test-graalvm, tao-headful, tao-a11y). This fixes the three lint errors. Behaviour doesn't change.

Minimal reproduction

./gradlew preMerge

Setup: nucleus-3.0 at d975bba, Ubuntu locally, and the gradle job of that commit's run on GitHub (run 41461175754).

Actual result:

e: .../internal/FlathubRepository.kt:216:87 Calling !! on a nullable type will throw a NullPointerException at runtime in case the value is null. It should be avoided. [UnsafeCallOnNullableType]
e: .../tasks/AbstractGenerateFlathubRepositoryTask.kt:135:51 "%02x".format(it) uses implicitly default locale for string formatting. [ImplicitDefaultLocale]
examples/lab/app/build.gradle.kts:234:121 Exceeded max line length (120) (cannot be auto-corrected) (standard:max-line-length)

Root cause and fix

• FlathubRepository: the URL list kept nullable values through a filter, so it needed !! afterwards. mapNotNull drops the nulls and keeps the type non-null.
• AbstractGenerateFlathubRepositoryTask: uses Locale.ROOT, like the other %02x digests in the plugin.
• examples/lab/app/build.gradle.kts: splits the screenshot base URL across two lines. The resulting string is the same.

Testing

On Ubuntu Linux: ./gradlew preMerge --continue fails with the three errors above before this change and passes after it.

Not tested: Flathub generation end to end, and macOS or Windows. Nothing here is platform-specific.

Checklist

• Targets nucleus-3.0
• Feature: discussed first in a GitHub discussion (linked above)
• One change, no unrelated reformatting
• ./gradlew preMerge passes
• Public API has KDoc, apiDump committed if the API changed
• I understand every line of this change and can answer review questions about it, whether or not AI tools were used
• Breaking change (explain above)

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