Uniform main and backport code

libs/entitlement/src/main/java/org/elasticsearch/entitlement/initialization/EntitlementCheckerUtils.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.entitlement.initialization;
+
+class EntitlementCheckerUtils {
+
+    /**
+     * Returns the "most recent" checker class compatible with the provided runtime Java version.
+     * For checkers, we have (optionally) version specific classes, each with a prefix (e.g. Java23).
+     * The mapping cannot be automatic, as it depends on the actual presence of these classes in the final Jar (see
+     * the various mainXX source sets).
+     */
+    static Class<?> getVersionSpecificCheckerClass(Class<?> baseClass, int javaVersion) {
+        String packageName = baseClass.getPackageName();
+        String baseClassName = baseClass.getSimpleName();
+
+        final String classNamePrefix;
+        if (javaVersion >= 23) {
+            // All Java version from 23 onwards will be able to use che checks in the Java23EntitlementChecker interface and implementation
+            classNamePrefix = "Java23";
+        } else {
+            // For any other Java version, the basic EntitlementChecker interface and implementation contains all the supported checks
+            classNamePrefix = "";
+        }
+        final String className = packageName + "." + classNamePrefix + baseClassName;
+        Class<?> clazz;
+        try {
+            clazz = Class.forName(className);
+        } catch (ClassNotFoundException e) {
+            throw new AssertionError("entitlement lib cannot find entitlement class " + className, e);
+        }
+        return clazz;
+    }
+}

libs/entitlement/src/main/java/org/elasticsearch/entitlement/initialization/EntitlementInitialization.java

@@ -68,7 +68,11 @@ public static void initialize(Instrumentation inst) throws Exception {
             ensureClassesSensitiveToVerificationAreInitialized();
         }
 
-        DynamicInstrumentation.initialize(inst, getVersionSpecificCheckerClass(EntitlementChecker.class), verifyBytecode);
+        DynamicInstrumentation.initialize(
+            inst,
+            EntitlementCheckerUtils.getVersionSpecificCheckerClass(EntitlementChecker.class, Runtime.version().feature()),
+            verifyBytecode
+        );
     }
 
     private static PolicyManager createPolicyManager() {
@@ -108,39 +112,13 @@ private static void ensureClassesSensitiveToVerificationAreInitialized() {
         }
     }
 
-    /**
-     * Returns the "most recent" checker class compatible with the current runtime Java version.
-     * For checkers, we have (optionally) version specific classes, each with a prefix (e.g. Java23).
-     * The mapping cannot be automatic, as it depends on the actual presence of these classes in the final Jar (see
-     * the various mainXX source sets).
-     */
-    private static Class<?> getVersionSpecificCheckerClass(Class<?> baseClass) {
-        String packageName = baseClass.getPackageName();
-        String baseClassName = baseClass.getSimpleName();
-        int javaVersion = Runtime.version().feature();
-
-        final String classNamePrefix;
-        if (javaVersion >= 23) {
-            // All Java version from 23 onwards will be able to use che checks in the Java23EntitlementChecker interface and implementation
-            classNamePrefix = "Java23";
-        } else {
-            // For any other Java version, the basic EntitlementChecker interface and implementation contains all the supported checks
-            classNamePrefix = "";
-        }
-        final String className = packageName + "." + classNamePrefix + baseClassName;
-        Class<?> clazz;
-        try {
-            clazz = Class.forName(className);
-        } catch (ClassNotFoundException e) {
-            throw new AssertionError("entitlement lib cannot find entitlement class " + className, e);
-        }
-        return clazz;
-    }
-
     private static ElasticsearchEntitlementChecker initChecker() {
         final PolicyManager policyManager = createPolicyManager();
 
-        final Class<?> clazz = getVersionSpecificCheckerClass(ElasticsearchEntitlementChecker.class);
+        final Class<?> clazz = EntitlementCheckerUtils.getVersionSpecificCheckerClass(
+            ElasticsearchEntitlementChecker.class,
+            Runtime.version().feature()
+        );
 
         Constructor<?> constructor;
         try {