chore: require a fixed 'major.minor.patch' Java version to be installed

Signed-off-by: Jendrik Johannes <[email protected]>

build-logic/project-plugins/src/main/kotlin/com.hedera.hashgraph.java.gradle.kts

@@ -38,33 +38,18 @@ plugins {
 version =
     providers.fileContents(rootProject.layout.projectDirectory.versionTxt()).asText.get().trim()
 
-// Fail the build if Gradle is started with an old version of Java
-val MIN_JAVA_VERSION = JavaVersion.VERSION_21
-val CUR_JAVA_VERSION = JavaVersion.current()
-
-if (CUR_JAVA_VERSION.ordinal < MIN_JAVA_VERSION.ordinal) {
-    throw StopExecutionException(
-        "ERROR: Gradle is started with Java " +
-            CUR_JAVA_VERSION +
-            ". This project requires running Gradle with Java " +
-            MIN_JAVA_VERSION +
-            " or above." +
-            " Please check your JAVA_HOME and/or PATH and configure the default JDK to use Java version " +
-            MIN_JAVA_VERSION +
-            " or above."
+// Fail the build if Gradle is started with a Java version that does not exactly match
+val javaVersion = "21.0.1"
+val currentJavaVersion = providers.systemProperty("java.version").get()
+
+if (currentJavaVersion != javaVersion) {
+    throw RuntimeException(
+        "Gradle runs with Java $currentJavaVersion. This project requires Gradle to run with Java $javaVersion. " +
+            "\n - From commandline: change JAVA_HOME and/or PATH to point at Java $javaVersion installation." +
+            "\n - From IntelliJ: change 'Gradle JVM' in 'Gradle Settings' to point at Java $javaVersion installation."
     )
 }
 
-java {
-    sourceCompatibility = MIN_JAVA_VERSION
-    targetCompatibility = MIN_JAVA_VERSION
-
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(21)
-        vendor = JvmVendorSpec.ADOPTIUM
-    }
-}
-
 configurations.all {
     // In case published versions of a module are also available, always prefer the local one
     resolutionStrategy.preferProjectModules()
@@ -148,9 +133,10 @@ tasks.withType<JavaCompile>().configureEach {
     // By default, Gradle only tracks the major version as defined in the toolchain (e.g. 17).
     // Since the full version is encoded in 'module-info.class' files, it should be tracked as
     // it otherwise leads to wrong build cache hits.
-    inputs.property("fullJavaVersion", providers.systemProperty("java.version"))
+    inputs.property("fullJavaVersion", currentJavaVersion)
 
     options.encoding = "UTF-8"
+    options.isFork = true // run compiler in separate JVM process (independent of toolchain setup)
 
     doLast {
         // Make sure consistent line ending are used in files generated by annotation processors by

build-logic/settings-plugins/build.gradle.kts

@@ -16,7 +16,4 @@
 
 plugins { `kotlin-dsl` }
 
-dependencies {
-    implementation("org.gradle.toolchains:foojay-resolver:0.7.0")
-    implementation("com.gradle:gradle-enterprise-gradle-plugin:3.15.1")
-}
+dependencies { implementation("com.gradle:gradle-enterprise-gradle-plugin:3.15.1") }

build-logic/settings-plugins/src/main/kotlin/com.hedera.hashgraph.settings.settings.gradle.kts

@@ -22,10 +22,7 @@ pluginManagement {
     }
 }
 
-plugins {
-    id("com.gradle.enterprise")
-    id("org.gradle.toolchains.foojay-resolver-convention")
-}
+plugins { id("com.gradle.enterprise") }
 
 // Enable Gradle Build Scan
 gradleEnterprise {