Make use of jvmToolchain for building the project.

[psteiger]

This allows for a more repeatable, predictable build between different local configurations.

On Kotlin modules, this is achieved by adding the following to project-level build.gradle:

kotlin {
  jvmToolchain(11)
}

On Java modules,

java {
  toolchain {
    languageVersion.set(JavaLanguageVersion.of(11))
  }
}

For non-Android Kotlin, when using the JVM Toolchain, the following is not needed anymore:

sourceCompatibility = deps.build.javaVersion.toString()
targetCompatibility = deps.build.javaVersion.toString()

For Android Kotlin modules, because of a bug present in AGP 7.4.x up to 8.1.0-alpha08, the following is still needed:

android {
    compileOptions {
        sourceCompatibility = <MAJOR_JDK_VERSION>
        targetCompatibility = <MAJOR_JDK_VERSION>
    }
}

Because AGP is bundled with the Android IntelliJ IDEA plugin, we cannot upgrade it (maximum supported version is 7.4 on 2023.1.1). We should open a new issue for removing above configuration block when a newer stable IntelliJ IDEA version ships with support for AGP 8.1.0.alpha09 or higher

Fixes #584

[tyvsmith]

We should probably apply this by default to all build targets (with the couple exceptions until we convert/fix them), so this isn't managed in ~20 spots.

[psteiger]

Agreed with the general statement of centralizing Kotlin module configurations. I can try to move those two to the project-level build.gradle.

With that said, the reason I did not do it on our project-level build.gradle is IMO we do config centralization poorly, in a non-Gradle-idiomatic way. We should probably be using a Gradle conventions plugin instead of those hard-to-read (to me) configurations at project-level, either built from buildSrc or includedBuilds, then we could just apply the plugin like

plugins {
 id("ribs-kotlin-convention-plugin")
}

This seems to be the Gradle-way for applying common configurations between different modules.

Perhaps we could open an issue to improve on that.

[tyvsmith]

Agreed. Let's punt this, and create an issue for the plugin, as well as moving the remaining java modules over and enabling explicitApi on the outlier.