build: bump build toolchain to JDK 17, keep Java 8 bytecode target

Gradle 9's default checkstyle toolVersion (~10.21+) requires Java 11+
to run, but every module pinned a Java 8 toolchain, so Gradle routed
the Checkstyle task's launcher through JDK 8 and the Ant task class
(class file version 55) failed to load on the JDK 8 runtime.

Rather than pin an old checkstyle or splice a separate launcher just
for Checkstyle, bump the build toolchain to JDK 17 in every module
and set `options.release = 8` on the library modules. Net effect:

- compile/checkstyle/javadoc all run on the same modern JVM
- published jars still contain class file version 52 (Java 8) — the
  library's consumer baseline is unchanged (verified on ImGui.class)
- CI only needs to install JDK 17 (dropped the dual 8+17 setup)

Also bump foojay-resolver-convention 0.10.0 -> 1.0.0. Gradle 9
removed JvmVendorSpec.IBM_SEMERU; the 0.10.0 plugin references it in
its <clinit>, so any local build that has to download a toolchain
(no matching JDK already installed) crashes with NoSuchFieldError
before reaching the task graph. CI didn't hit this because
setup-java pre-installs the JDKs.

Verified: ./gradlew buildAll green on JDK 25 / macOS arm64; javap on
the produced ImGui.class reports major version 52.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: phraktle

.github/workflows/ci.yml

@@ -24,9 +24,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           distribution: liberica
-          java-version: |
-            8
-            17
+          java-version: 17
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v5
@@ -73,9 +71,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           distribution: liberica
-          java-version: |
-            8
-            17
+          java-version: 17
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v5
@@ -162,9 +158,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           distribution: liberica
-          java-version: |
-            8
-            17
+          java-version: 17
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v5

example/build.gradle

@@ -4,7 +4,7 @@ plugins {
 
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(8))
+        languageVersion.set(JavaLanguageVersion.of(17))
     }
 }
 

imgui-app/build.gradle

@@ -8,10 +8,14 @@ plugins {
 
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(8))
+        languageVersion.set(JavaLanguageVersion.of(17))
     }
 }
 
+tasks.withType(JavaCompile).configureEach {
+    options.release.set(8)
+}
+
 dependencies {
     api platform("org.lwjgl:lwjgl-bom:$lwjglVersion")
 

imgui-binding-natives/build.gradle

@@ -6,7 +6,7 @@ plugins {
 
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(8))
+        languageVersion.set(JavaLanguageVersion.of(17))
     }
 }
 

imgui-binding/build.gradle

@@ -10,10 +10,14 @@ plugins {
 
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(8))
+        languageVersion.set(JavaLanguageVersion.of(17))
     }
 }
 
+tasks.withType(JavaCompile).configureEach {
+    options.release.set(8)
+}
+
 dependencies {
     testImplementation("org.junit.jupiter:junit-jupiter-api:5.13.4")
     testImplementation("org.junit.jupiter:junit-jupiter-engine:5.13.4")

imgui-lwjgl3/build.gradle

@@ -7,10 +7,14 @@ plugins {
 
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(8))
+        languageVersion.set(JavaLanguageVersion.of(17))
     }
 }
 
+tasks.withType(JavaCompile).configureEach {
+    options.release.set(8)
+}
+
 dependencies {
     implementation platform("org.lwjgl:lwjgl-bom:$lwjglVersion")
 

settings.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    id("org.gradle.toolchains.foojay-resolver-convention") version("0.10.0")
+    id("org.gradle.toolchains.foojay-resolver-convention") version("1.0.0")
 }
 
 rootProject.name = "imgui-java"