Fix incomplete AssertJ assertions

Closes gh-30743

spring-context/src/test/java/org/springframework/jmx/export/MBeanExporterTests.java

@@ -102,7 +102,7 @@ public class MBeanExporterTests extends AbstractMBeanServerTests {
 		exporter.setNotificationListenerMappings(listeners);
 		assertThatExceptionOfType(MBeanExportException.class).as("NotificationListener on a non-existent MBean").isThrownBy(() ->
 				start(exporter))
-			.satisfies(ex -> assertThat(ex.contains(InstanceNotFoundException.class)));
+			.satisfies(ex -> assertThat(ex.contains(InstanceNotFoundException.class)).isTrue());
 	}
 
 	@Test

spring-test/src/test/java/org/springframework/test/context/junit/jupiter/event/JUnitJupiterApplicationEventsIntegrationTests.java

@@ -264,10 +264,10 @@ class JUnitJupiterApplicationEventsIntegrationTests {
 			context.publishEvent(new CustomEvent("sync"));
 
 			Awaitility.await().atMost(Durations.ONE_SECOND)
-					.untilAsserted(() -> assertThat(assertThat(this.applicationEvents.stream(CustomEvent.class))
+					.untilAsserted(() -> assertThat(this.applicationEvents.stream(CustomEvent.class))
 							.singleElement()
 							.extracting(CustomEvent::getMessage, InstanceOfAssertFactories.STRING)
-							.isEqualTo("sync")));
+							.isEqualTo("sync"));
 		}
 
 	}

spring-test/src/test/java/org/springframework/test/context/junit4/event/JUnit4ApplicationEventsAsyncIntegrationTests.java

@@ -71,10 +71,10 @@ public class JUnit4ApplicationEventsAsyncIntegrationTests {
 		context.publishEvent(new CustomEvent("sync"));
 
 		Awaitility.await().atMost(Durations.ONE_SECOND)
-				.untilAsserted(() -> assertThat(assertThat(this.applicationEvents.stream(CustomEvent.class))
+				.untilAsserted(() -> assertThat(this.applicationEvents.stream(CustomEvent.class))
 						.singleElement()
 						.extracting(CustomEvent::getMessage, InstanceOfAssertFactories.STRING)
-						.isEqualTo("sync")));
+						.isEqualTo("sync"));
 	}
 
 

spring-test/src/test/java/org/springframework/test/context/testng/event/TestNGApplicationEventsAsyncIntegrationTests.java

@@ -65,10 +65,10 @@ class TestNGApplicationEventsAsyncIntegrationTests extends AbstractTestNGSpringC
 		context.publishEvent(new CustomEvent("asyncConsumption"));
 
 		Awaitility.await().atMost(Durations.ONE_SECOND)
-				.untilAsserted(() -> assertThat(assertThat(this.applicationEvents.stream(CustomEvent.class))
+				.untilAsserted(() -> assertThat(this.applicationEvents.stream(CustomEvent.class))
 						.singleElement()
 						.extracting(CustomEvent::getMessage, InstanceOfAssertFactories.STRING)
-						.isEqualTo("asyncConsumption")));
+						.isEqualTo("asyncConsumption"));
 	}