Expose isClosed() method on AbstractApplicationContext

Closes gh-33058

spring-context/src/main/java/org/springframework/context/ConfigurableApplicationContext.java

@@ -242,6 +242,18 @@ public interface ConfigurableApplicationContext extends ApplicationContext, Life
 	@Override
 	void close();
 
+	/**
+	 * Return whether this context has been closed already, that is,
+	 * whether {@link #close()} has been called on an active context
+	 * in order to initiate its shutdown.
+	 * <p>Note: This does not indicate whether context shutdown has completed.
+	 * Use {@link #isActive()} for differentiating between those scenarios:
+	 * a context becomes inactive once it has been fully shut down and the
+	 * original {@code close()} call has returned.
+	 * @since 6.2
+	 */
+	boolean isClosed();
+
 	/**
 	 * Determine whether this application context is active, that is,
 	 * whether it has been refreshed at least once and has not been closed yet.

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -1222,6 +1222,11 @@ protected void onClose() {
 		// For subclasses: do nothing by default.
 	}
 
+	@Override
+	public boolean isClosed() {
+		return this.closed.get();
+	}
+
 	@Override
 	public boolean isActive() {
 		return this.active.get();