[IcebergIO] Run xlang wrapper validation expansion service on Java 17

The cross-language wrapper validation launches the io expansion-service jar from Python via JAVA_HOME. That jar bundles IcebergIO, now Java 17 bytecode, so launching it on the default Java 11 fails with UnsupportedClassVersionError.

createCrossLanguageUsingJavaExpansionTask was missing the JAVA_HOME redirect that #38974 added to the other cross-language task factories. Add it, defaulting to java17Home (already provided to this build) so bundled Java 17 IOs can be loaded.

Author: peterphitran

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

@@ -2715,6 +2715,12 @@ class BeamModulePlugin implements Plugin<Project> {
       def usesDataflowRunner = config.pythonPipelineOptions.contains("--runner=TestDataflowRunner") || config.pythonPipelineOptions.contains("--runner=DataflowRunner")
       String ver = project.findProperty('testJavaVersion')
       def javaContainerSuffix = ver ? getSupportedJavaVersion(ver) : getSupportedJavaVersion()
+      // Resolve the JDK used to launch the Python-started expansion service (see the exec block
+      // below). Prefer the explicitly requested test JDK (-PtestJavaVersion); otherwise fall back
+      // to java17Home when provided. Some bundled IOs (e.g. IcebergIO) are compiled for Java 17, so
+      // the expansion service must run on a JDK that can load them.
+      String testJavaHome = ver ? project.findProperty("java${ver}Home") : null
+      String expansionServiceJavaHome = testJavaHome ?: project.findProperty('java17Home')
 
       // Sets up, collects, and runs Python pipeline tests
       project.tasks.register(config.name+"PythonUsingJava") {
@@ -2744,6 +2750,12 @@ class BeamModulePlugin implements Plugin<Project> {
           project.exec {
             // environment variable to indicate that jars have been built
             environment "EXPANSION_JARS", config.expansionProjectPaths
+            // Launch the expansion service on expansionServiceJavaHome when resolved, so that
+            // bundled Java 17 IOs (e.g. IcebergIO) can be loaded. The other cross-language task
+            // factories apply the same JAVA_HOME redirect.
+            if (expansionServiceJavaHome) {
+              environment "JAVA_HOME", expansionServiceJavaHome
+            }
             String additionalDependencyCmd = ""
             if (config.additionalDeps != null && !config.additionalDeps.isEmpty()){
               additionalDependencyCmd = "&& pip install ${config.additionalDeps.join(' ')} "