Fix RateLimiter test to depend on the permission

* Add `RateLimiterRequestHandlerAdvice.getRateLimiter()` to get access
to the configured `RateLimiter` for possible low-level operations and
management
* Fix the `RateLimiterRequestHandlerAdviceTests` to calculate the sleep
based on the `reservePermission()` plus `REFRESH_PERIOD`

spring-integration-core/src/main/java/org/springframework/integration/handler/advice/RateLimiterRequestHandlerAdvice.java

@@ -117,6 +117,14 @@ public class RateLimiterRequestHandlerAdvice extends AbstractRequestHandlerAdvic
 		return this.rateLimiter.getMetrics();
 	}
 
+	/**
+	 * Get a {@link RateLimiter} which is configured for this advice.
+	 * @return the {@link RateLimiter} for this advice.
+	 */
+	public RateLimiter getRateLimiter() {
+		return this.rateLimiter;
+	}
+
 	@Override
 	protected Object doInvoke(ExecutionCallback callback, Object target, Message<?> message) throws Exception {
 		CheckedFunction0<Object> restrictedCall =

spring-integration-core/src/test/java/org/springframework/integration/handler/advice/RateLimiterRequestHandlerAdviceTests.java

@@ -20,6 +20,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 import java.time.Duration;
+import java.util.concurrent.TimeUnit;
 
 import org.junit.jupiter.api.Test;
 
@@ -47,12 +48,17 @@ import io.github.resilience4j.ratelimiter.RequestNotPermitted;
 @SpringJUnitConfig
 public class RateLimiterRequestHandlerAdviceTests {
 
+	private static final Duration REFRESH_PERIOD = Duration.ofMillis(500);
+
 	@Autowired
 	private MessageChannel requestChannel;
 
 	@Autowired
 	private PollableChannel resultChannel;
 
+	@Autowired
+	private RateLimiterRequestHandlerAdvice rateLimiterRequestHandlerAdvice;
+
 	@Test
 	void testRateLimiter() throws InterruptedException {
 		Message<?> testMessage = new GenericMessage<>("test");
@@ -63,7 +69,11 @@ public class RateLimiterRequestHandlerAdviceTests {
 				.withCauseInstanceOf(RequestNotPermitted.class)
 				.withMessageContaining("Rate limit exceeded for: ");
 
-		Thread.sleep(200);
+		long howLongToWait =
+				this.rateLimiterRequestHandlerAdvice.getRateLimiter()
+						.reservePermission(Duration.ofSeconds(10));
+
+		TimeUnit.NANOSECONDS.sleep(howLongToWait + REFRESH_PERIOD.toNanos());
 
 		this.requestChannel.send(testMessage);
 
@@ -77,11 +87,12 @@ public class RateLimiterRequestHandlerAdviceTests {
 
 		@Bean
 		public RateLimiterRequestHandlerAdvice rateLimiterRequestHandlerAdvice() {
-			return new RateLimiterRequestHandlerAdvice(RateLimiterConfig.custom()
-					.timeoutDuration(Duration.ofMillis(100))
-					.limitRefreshPeriod(Duration.ofMillis(500))
-					.limitForPeriod(1)
-					.build());
+			return new RateLimiterRequestHandlerAdvice(
+					RateLimiterConfig.custom()
+							.timeoutDuration(Duration.ofMillis(100))
+							.limitRefreshPeriod(REFRESH_PERIOD)
+							.limitForPeriod(1)
+							.build());
 		}
 
 		@Bean