Restore NullMarked tests

buildSrc/src/test/java/org/springframework/boot/build/architecture/ArchitectureCheckTests.java

@@ -270,6 +270,19 @@ void whenBeanMethodExposesNonPrivateTypeShouldSucceedAndWriteEmptyReport(Task ta
 		build(this.gradleBuild.withDependencies(SPRING_CONTEXT), task);
 	}
 
+	@Test
+	void whenPackageIsNotAnnotatedWithNullMarkedWithMainSourcesShouldFailAndWriteEmptyReport() throws IOException {
+		prepareTask(Task.CHECK_ARCHITECTURE_MAIN, "nullmarked/notannotated");
+		buildAndFail(this.gradleBuild.withNullMarked(true), Task.CHECK_ARCHITECTURE_MAIN,
+				"Package org.springframework.boot.build.architecture.nullmarked.notannotated is not annotated with @NullMarked");
+	}
+
+	@Test
+	void whenPackageIsNotAnnotatedWithNullMarkedWithTestSourcesShouldSucceedAndWriteEmptyReport() throws IOException {
+		prepareTask(Task.CHECK_ARCHITECTURE_TEST, "nullmarked/notannotated");
+		build(this.gradleBuild.withNullMarked(true), Task.CHECK_ARCHITECTURE_TEST);
+	}
+
 	private void prepareTask(Task task, String... sourceDirectories) throws IOException {
 		for (String sourceDirectory : sourceDirectories) {
 			FileSystemUtils.copyRecursively(

buildSrc/src/test/java/org/springframework/boot/build/architecture/nullmarked/notannotated/TestClass.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.build.architecture.nullmarked.notannotated;
+
+public class TestClass {
+
+}