Silently fall back to platform threads when virtual=true on Java 17

Per Concurrency 3.1 spec: "When running on Java SE 17, the true value
behaves the same as the false value and results in platform threads
being created rather than virtual threads."

Previously, virtual=true unconditionally called VirtualThreadHelper
methods which throw UnsupportedOperationException on Java 17. Now
checks VirtualThreadHelper.isSupported() first and falls through to
platform thread creation when virtual threads are unavailable.

Author: rzo1

container/openejb-core/src/main/java/org/apache/openejb/cdi/concurrency/AsynchronousInterceptor.java

@@ -130,8 +130,9 @@ private Object aroundInvokeScheduled(final InvocationContext ctx, final Asynchro
         final ContextServiceImpl.Snapshot snapshot = ctxService.snapshot(null);
 
         // Per spec, scheduled async methods are NOT subject to maxAsync constraints.
-        // Use the default MSES's delegate for the trigger loop — it is not constrained
-        // by the referenced executor's maxAsync setting.
+        // Use the default MSES's delegate for both the trigger timer and method execution —
+        // it is not constrained by the referenced executor's maxAsync setting.
+        // Context propagation (security, TX, etc.) is handled via ContextService.snapshot/enter/exit.
         final ManagedScheduledExecutorServiceImpl defaultMses =
                 ManagedScheduledExecutorServiceImplFactory.lookup("java:comp/DefaultManagedScheduledExecutorService");
         final ScheduledExecutorService triggerDelegate = defaultMses.getDelegate();

container/openejb-core/src/main/java/org/apache/openejb/resource/thread/ManagedExecutorServiceImplFactory.java

@@ -81,7 +81,9 @@ public ManagedExecutorServiceImpl create(final ContextServiceImpl contextService
     }
 
     private ExecutorService createExecutorService() {
-        if (virtual) {
+        // Per spec: "When running on Java SE 17, the true value behaves the same as the
+        // false value and results in platform threads being created rather than virtual threads."
+        if (virtual && VirtualThreadHelper.isSupported()) {
             final ThreadFactory vtFactory = VirtualThreadHelper.newVirtualThreadFactory(ManagedThreadFactoryImpl.DEFAULT_PREFIX);
             return VirtualThreadHelper.newVirtualThreadPerTaskExecutor(vtFactory);
         }

container/openejb-core/src/main/java/org/apache/openejb/threads/impl/ManagedThreadFactoryImpl.java

@@ -55,7 +55,9 @@ public ManagedThreadFactoryImpl(final String prefix, final Integer priority, fin
     public Thread newThread(final Runnable r) {
         final CURunnable wrapper = new CURunnable(r, contextService);
 
-        if (virtual) {
+        // Per spec: "When running on Java SE 17, the true value behaves the same as the
+        // false value and results in platform threads being created rather than virtual threads."
+        if (virtual && VirtualThreadHelper.isSupported()) {
             // Virtual threads do NOT implement ManageableThread (spec 3.4.4)
             // Priority and daemon settings are ignored for virtual threads
             final Thread thread = VirtualThreadHelper.newVirtualThread(prefix, ID.incrementAndGet(), wrapper);