Restore Java 8 source/target compatibility for MobiVM consumers

[Copilot]

gdx-pay had moved its Java compilation target to 11, which breaks libGDX iOS/MobiVM projects that still require Java 8-compatible bytecode. This change brings the build back in line with the rest of the libGDX ecosystem by targeting Java 8 for both source and output.

• Build compatibility

  • Lower Java compilation settings from 11 to 8 in the shared Gradle JavaCompile configuration.
  • Apply the same Java 8 source/target settings in modules that were still hard-coding Java 11.

• Published artifact behavior

  • Set options.release = 8 when building on Java 9+ for non-Android Java compilation, so published Java artifacts are compiled against Java 8 APIs as well as emitted as Java 8 bytecode.
  • Skip options.release for Android library projects, because Android Gradle Plugin requires Java 8 builds to use only sourceCompatibility and targetCompatibility.

• Scope

  • Updates only the Gradle build configuration for affected Java modules:
    • core
    • client
    • server
    • Android Amazon
    • iOS RoboVM Apple

tasks.withType(JavaCompile).configureEach {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_1_8
    if (JavaVersion.current().isJava9Compatible() && !project.plugins.hasPlugin('com.android.library')) {
        options.release.set(8)
    }
}

[keesvandieren]

@copilot compilation is failing, please fix the problems

[Copilot]

@copilot compilation is failing, please fix the problems

Fixed in dc68bfd. The CI failure was caused by applying --release 8 to Android compilation; the shared Gradle config now keeps Java 8 source/target compatibility but skips options.release for Android library projects.

[keesvandieren]

@obigu we've restored compatibility to 8. Still building with Java 17 as that is what we're currently using in our libgdx projects, and JDK 8 is a problem on Apple Silicon.