Add nullability annotations to tests in module/spring-boot-micrometer-metrics-test

See gh-47263

module/spring-boot-micrometer-metrics-test/build.gradle

@@ -35,3 +35,7 @@ dependencies {
 
 	testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

module/spring-boot-micrometer-metrics-test/src/test/java/org/springframework/boot/micrometer/metrics/test/autoconfigure/MetricsContextCustomizerFactoryTests.java

@@ -24,8 +24,11 @@ import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.mock.env.MockEnvironment;
 import org.springframework.test.context.ContextCustomizer;
+import org.springframework.test.context.ContextLoader;
+import org.springframework.test.context.MergedContextConfiguration;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link AutoConfigureMetrics} and {@link MetricsContextCustomizerFactory}
@@ -131,7 +134,8 @@ class MetricsContextCustomizerFactoryTests {
 	}
 
 	private void applyCustomizerToContext(ContextCustomizer customizer, ConfigurableApplicationContext context) {
-		customizer.customizeContext(context, null);
+		customizer.customizeContext(context,
+				new MergedContextConfiguration(getClass(), null, null, null, mock(ContextLoader.class)));
 	}
 
 	private ContextCustomizer createContextCustomizer(Class<?> testClass) {