Gradle: use new lazy tasks API when supported (Gradle 4.9+)

See https://docs.gradle.org/current/userguide/task_configuration_avoidance.html

This boils down to:

• using project.tasks.register instead of project.tasks.create
• moving call to project.afterEvaluate and dependsOn outside the configuration closure, and to act on the task (in project.afterEvaluate), use task.configure { … } as task would then actually be a TaskProvider.
• using configureEach instead of all
• using project.tasks.named(…).configure { … } instead of project.tasks[…].…

This can generally be done quite easily with a couple utility functions using version checks.

[tbroyer]

Do you have a patch of one of your own plugins migrating to new APIs (including if/ten/else to support older versions)? I can look into it next weekend.

The simplest is https://github.com/tbroyer/gradle-errorprone-plugin/commit/eb0f35b32b81a8f9d28f4b1aa790bac4b371b704 but only covers configureEach vs. all. https://github.com/tbroyer/gradle-errorprone-javacplugin-plugin/commit/e795a20cc1ef77f35ef3baf7c8d509f5546f3310 uses Kotlin extension methods; and finally I have https://github.com/tbroyer/gradle-apt-plugin/commit/5e8b10f76d13584ed54f183c771fbd10ec3036a0 and https://github.com/tbroyer/gradle-apt-plugin/commit/432509ec85d1ab49296d4f9b21fad876523c6a8a that delegate to one of many implementations depending on the Gradle version. HTH

[tbroyer]

Fwiw, the plugin could also use lazy configuration instead of conventionMapping, though that would mean bumping the minimum supported Gradle version to 4.3 (or maybe even 4.4). See https://docs.gradle.org/current/userguide/lazy_configuration.html

And wrt the lazy tasks API, I haven’t had any issue moving to that in my own plugins and builds; you of course have to be cautious and only do in the configure closures what cannot be done with a TaskProvider (hence moving forbiddenTask.dependsOn(task) outside the closure, to be resolved when forbiddenTask is realized, not the task)

I understand you’d rather do a release before making those changes though.