Add @API annotation and javadoc

Issue: #4135
Signed-off-by: yongjunhong <[email protected]>

Author: YongGoose

junit-vintage-engine/src/main/java/org/junit/vintage/engine/VintageTestEngine.java

@@ -11,6 +11,7 @@
 package org.junit.vintage.engine;
 
 import static org.apiguardian.api.API.Status.INTERNAL;
+import static org.apiguardian.api.API.Status.STABLE;
 import static org.junit.platform.engine.TestExecutionResult.successful;
 import static org.junit.vintage.engine.descriptor.VintageTestDescriptor.ENGINE_ID;
 
@@ -51,8 +52,29 @@ public final class VintageTestEngine implements TestEngine {
 
 	private static final int DEFAULT_THREAD_POOL_SIZE = Runtime.getRuntime().availableProcessors();
 	private static final int SHUTDOWN_TIMEOUT_SECONDS = 30;
-	private static final String PARALLEL_EXECUTION_ENABLED = "junit.vintage.execution.parallel.enabled";
-	private static final String PARALLEL_POOL_SIZE = "junit.vintage.execution.parallel.pool-size";
+
+	/**
+	 * Indicates whether parallel execution is enabled for the JUnit Vintage engine.
+	 *
+	 * <p>Set this property to {@code true} to enable parallel execution of tests.
+	 * Defaults to {@code false}.
+	 *
+	 * @since 5.12
+	 */
+	@API(status = STABLE, since = "5.12")
+	public static final String PARALLEL_EXECUTION_ENABLED = "junit.vintage.execution.parallel.enabled";
+
+	/**
+	 * Specifies the size of the thread pool to be used for parallel execution.
+	 *
+	 * <p>Set this property to an integer value to specify the number of threads
+	 * to be used for parallel execution. Defaults to the number of available
+	 * processors.
+	 *
+	 * @since 5.12
+	 */
+	@API(status = STABLE, since = "5.12")
+	public static final String PARALLEL_POOL_SIZE = "junit.vintage.execution.parallel.pool-size";
 
 	@Override
 	public String getId() {