Add nullability annotations to tests in build-plugin/spring-boot-maven-plugin

See gh-47263

build-plugin/spring-boot-maven-plugin/build.gradle

@@ -194,3 +194,15 @@ tasks.named("generateAntoraPlaybook") {
 tasks.named("dockerTest").configure {
 	dependsOn tasks.named("prepareMavenBinaries")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}
+
+tasks.named("compileIntTestJava") {
+	options.nullability.checking = "tests"
+}
+
+tasks.named("compileDockerTestJava") {
+	options.nullability.checking = "tests"
+}

build-plugin/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/AbstractArchiveIntegrationTests.java

@@ -36,6 +36,7 @@ import java.util.zip.ZipEntry;
 import org.assertj.core.api.AbstractAssert;
 import org.assertj.core.api.AssertProvider;
 import org.assertj.core.api.ListAssert;
+import org.jspecify.annotations.Nullable;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.contentOf;
@@ -95,7 +96,7 @@ abstract class AbstractArchiveIntegrationTests {
 		}
 	}
 
-	protected String getLayersIndexLocation() {
+	protected @Nullable String getLayersIndexLocation() {
 		return null;
 	}
 

build-plugin/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/JarIntegrationTests.java

@@ -29,6 +29,7 @@ import org.junit.jupiter.api.TestTemplate;
 import org.junit.jupiter.api.extension.ExtendWith;
 
 import org.springframework.boot.loader.tools.JarModeLibrary;
+import org.springframework.boot.loader.tools.LibraryCoordinates;
 import org.springframework.boot.testsupport.FileUtils;
 import org.springframework.util.FileSystemUtils;
 
@@ -389,10 +390,12 @@ class JarIntegrationTests extends AbstractArchiveIntegrationTests {
 	void repackagedJarContainsTheLayersIndexByDefault(MavenBuild mavenBuild) {
 		mavenBuild.project("jar-layered").execute((project) -> {
 			File repackaged = new File(project, "jar/target/jar-layered-0.0.1.BUILD-SNAPSHOT.jar");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			assertThat(jar(repackaged)).hasEntryWithNameStartingWith("BOOT-INF/classes/")
 				.hasEntryWithNameStartingWith("BOOT-INF/lib/jar-release")
 				.hasEntryWithNameStartingWith("BOOT-INF/lib/jar-snapshot")
-				.hasEntryWithNameStartingWith("BOOT-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId());
+				.hasEntryWithNameStartingWith("BOOT-INF/lib/" + coordinates.getArtifactId());
 			try (JarFile jarFile = new JarFile(repackaged)) {
 				Map<String, List<String>> layerIndex = readLayerIndex(jarFile);
 				assertThat(layerIndex.keySet()).containsExactly("dependencies", "spring-boot-loader",
@@ -412,10 +415,12 @@ class JarIntegrationTests extends AbstractArchiveIntegrationTests {
 	void whenJarIsRepackagedWithTheLayersDisabledDoesNotContainLayersIndex(MavenBuild mavenBuild) {
 		mavenBuild.project("jar-layered-disabled").execute((project) -> {
 			File repackaged = new File(project, "jar/target/jar-layered-0.0.1.BUILD-SNAPSHOT.jar");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			assertThat(jar(repackaged)).hasEntryWithNameStartingWith("BOOT-INF/classes/")
 				.hasEntryWithNameStartingWith("BOOT-INF/lib/jar-release")
 				.hasEntryWithNameStartingWith("BOOT-INF/lib/jar-snapshot")
-				.hasEntryWithNameStartingWith("BOOT-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId())
+				.hasEntryWithNameStartingWith("BOOT-INF/lib/" + coordinates.getArtifactId())
 				.doesNotHaveEntryWithName("BOOT-INF/layers.idx");
 		});
 	}
@@ -424,11 +429,12 @@ class JarIntegrationTests extends AbstractArchiveIntegrationTests {
 	void whenJarIsRepackagedWithToolsExclude(MavenBuild mavenBuild) {
 		mavenBuild.project("jar-no-tools").execute((project) -> {
 			File repackaged = new File(project, "jar/target/jar-no-tools-0.0.1.BUILD-SNAPSHOT.jar");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			assertThat(jar(repackaged)).hasEntryWithNameStartingWith("BOOT-INF/classes/")
 				.hasEntryWithNameStartingWith("BOOT-INF/lib/jar-release")
 				.hasEntryWithNameStartingWith("BOOT-INF/lib/jar-snapshot")
-				.doesNotHaveEntryWithNameStartingWith(
-						"BOOT-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId());
+				.doesNotHaveEntryWithNameStartingWith("BOOT-INF/lib/" + coordinates.getArtifactId());
 		});
 	}
 
@@ -496,18 +502,22 @@ class JarIntegrationTests extends AbstractArchiveIntegrationTests {
 				throw new RuntimeException(ex);
 			}
 		});
-		return jarHash.get();
+		String hash = jarHash.get();
+		assertThat(hash).isNotNull();
+		return hash;
 	}
 
 	@TestTemplate
 	void whenJarIsRepackagedWithOutputTimestampConfiguredThenLibrariesAreSorted(MavenBuild mavenBuild) {
 		mavenBuild.project("jar-output-timestamp").execute((project) -> {
 			File repackaged = new File(project, "target/jar-output-timestamp-0.0.1.BUILD-SNAPSHOT.jar");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			List<String> sortedLibs = Arrays.asList("BOOT-INF/lib/commons-logging", "BOOT-INF/lib/jakarta.servlet-api",
 					"BOOT-INF/lib/jspecify", "BOOT-INF/lib/micrometer-commons", "BOOT-INF/lib/micrometer-observation",
 					"BOOT-INF/lib/spring-aop", "BOOT-INF/lib/spring-beans",
-					"BOOT-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId(),
-					"BOOT-INF/lib/spring-context", "BOOT-INF/lib/spring-core", "BOOT-INF/lib/spring-expression");
+					"BOOT-INF/lib/" + coordinates.getArtifactId(), "BOOT-INF/lib/spring-context",
+					"BOOT-INF/lib/spring-core", "BOOT-INF/lib/spring-expression");
 			assertThat(jar(repackaged)).entryNamesInPath("BOOT-INF/lib/")
 				.zipSatisfy(sortedLibs,
 						(String jarLib, String expectedLib) -> assertThat(jarLib).startsWith(expectedLib));

build-plugin/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/MavenBuild.java

@@ -43,7 +43,9 @@ import org.apache.maven.shared.invoker.InvocationRequest;
 import org.apache.maven.shared.invoker.InvocationResult;
 import org.apache.maven.shared.invoker.Invoker;
 import org.apache.maven.shared.invoker.MavenInvocationException;
+import org.jspecify.annotations.Nullable;
 
+import org.springframework.util.Assert;
 import org.springframework.util.FileSystemUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -67,9 +69,9 @@ class MavenBuild {
 
 	private final Properties properties = new Properties();
 
-	private ProjectCallback preparation;
+	private @Nullable ProjectCallback preparation;
 
-	private File projectDir;
+	private @Nullable File projectDir;
 
 	MavenBuild(File home) {
 		this.home = home;
@@ -133,6 +135,7 @@ class MavenBuild {
 		InvocationRequest request = new DefaultInvocationRequest();
 		try {
 			Path destination = this.temp.toPath();
+			Assert.notNull(this.projectDir, "'projectDir' must not be null");
 			Path source = this.projectDir.toPath();
 			Files.walkFileTree(source, new SimpleFileVisitor<>() {
 

build-plugin/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/Versions.java

@@ -23,6 +23,8 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Provides access to various versions.
  *
@@ -49,7 +51,7 @@ class Versions {
 		}
 	}
 
-	String get(String name) {
+	@Nullable String get(String name) {
 		return this.versions.get(name);
 	}
 

build-plugin/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/WarIntegrationTests.java

@@ -30,6 +30,7 @@ import org.junit.jupiter.api.TestTemplate;
 import org.junit.jupiter.api.extension.ExtendWith;
 
 import org.springframework.boot.loader.tools.JarModeLibrary;
+import org.springframework.boot.loader.tools.LibraryCoordinates;
 import org.springframework.boot.testsupport.FileUtils;
 import org.springframework.util.FileSystemUtils;
 
@@ -113,13 +114,17 @@ class WarIntegrationTests extends AbstractArchiveIntegrationTests {
 				throw new RuntimeException(ex);
 			}
 		});
-		return warHash.get();
+		String hash = warHash.get();
+		assertThat(hash).isNotNull();
+		return hash;
 	}
 
 	@TestTemplate
 	void whenWarIsRepackagedWithOutputTimestampConfiguredThenLibrariesAreSorted(MavenBuild mavenBuild) {
 		mavenBuild.project("war-output-timestamp").execute((project) -> {
 			File repackaged = new File(project, "target/war-output-timestamp-0.0.1.BUILD-SNAPSHOT.war");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			List<String> sortedLibs = Arrays.asList(
 					// these libraries are copied from the original war, sorted when
 					// packaged by Maven
@@ -128,7 +133,7 @@ class WarIntegrationTests extends AbstractArchiveIntegrationTests {
 					"WEB-INF/lib/spring-context", "WEB-INF/lib/spring-core", "WEB-INF/lib/spring-expression",
 					// these libraries are contributed by Spring Boot repackaging, and
 					// sorted separately
-					"WEB-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId());
+					"WEB-INF/lib/" + coordinates.getArtifactId());
 			assertThat(jar(repackaged)).entryNamesInPath("WEB-INF/lib/")
 				.zipSatisfy(sortedLibs,
 						(String jarLib, String expectedLib) -> assertThat(jarLib).startsWith(expectedLib));
@@ -148,10 +153,12 @@ class WarIntegrationTests extends AbstractArchiveIntegrationTests {
 	void repackagedWarContainsTheLayersIndexByDefault(MavenBuild mavenBuild) {
 		mavenBuild.project("war-layered").execute((project) -> {
 			File repackaged = new File(project, "war/target/war-layered-0.0.1.BUILD-SNAPSHOT.war");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			assertThat(jar(repackaged)).hasEntryWithNameStartingWith("WEB-INF/classes/")
 				.hasEntryWithNameStartingWith("WEB-INF/lib/jar-release")
 				.hasEntryWithNameStartingWith("WEB-INF/lib/jar-snapshot")
-				.hasEntryWithNameStartingWith("WEB-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId());
+				.hasEntryWithNameStartingWith("WEB-INF/lib/" + coordinates.getArtifactId());
 			try (JarFile jarFile = new JarFile(repackaged)) {
 				Map<String, List<String>> layerIndex = readLayerIndex(jarFile);
 				assertThat(layerIndex.keySet()).containsExactly("dependencies", "spring-boot-loader",
@@ -176,10 +183,12 @@ class WarIntegrationTests extends AbstractArchiveIntegrationTests {
 	void whenWarIsRepackagedWithTheLayersDisabledDoesNotContainLayersIndex(MavenBuild mavenBuild) {
 		mavenBuild.project("war-layered-disabled").execute((project) -> {
 			File repackaged = new File(project, "war/target/war-layered-0.0.1.BUILD-SNAPSHOT.war");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			assertThat(jar(repackaged)).hasEntryWithNameStartingWith("WEB-INF/classes/")
 				.hasEntryWithNameStartingWith("WEB-INF/lib/jar-release")
 				.hasEntryWithNameStartingWith("WEB-INF/lib/jar-snapshot")
-				.hasEntryWithNameStartingWith("WEB-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId())
+				.hasEntryWithNameStartingWith("WEB-INF/lib/" + coordinates.getArtifactId())
 				.doesNotHaveEntryWithName("WEB-INF/layers.idx");
 		});
 	}
@@ -188,11 +197,12 @@ class WarIntegrationTests extends AbstractArchiveIntegrationTests {
 	void whenWarIsRepackagedWithToolsExclude(MavenBuild mavenBuild) {
 		mavenBuild.project("war-no-tools").execute((project) -> {
 			File repackaged = new File(project, "war/target/war-no-tools-0.0.1.BUILD-SNAPSHOT.war");
+			LibraryCoordinates coordinates = JarModeLibrary.TOOLS.getCoordinates();
+			assertThat(coordinates).isNotNull();
 			assertThat(jar(repackaged)).hasEntryWithNameStartingWith("WEB-INF/classes/")
 				.hasEntryWithNameStartingWith("WEB-INF/lib/jar-release")
 				.hasEntryWithNameStartingWith("WEB-INF/lib/jar-snapshot")
-				.doesNotHaveEntryWithNameStartingWith(
-						"WEB-INF/lib/" + JarModeLibrary.TOOLS.getCoordinates().getArtifactId());
+				.doesNotHaveEntryWithNameStartingWith("WEB-INF/lib/" + coordinates.getArtifactId());
 		});
 	}
 

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/ArtifactsLibrariesTests.java

@@ -38,6 +38,7 @@ import org.mockito.junit.jupiter.MockitoExtension;
 
 import org.springframework.boot.loader.tools.Library;
 import org.springframework.boot.loader.tools.LibraryCallback;
+import org.springframework.boot.loader.tools.LibraryCoordinates;
 import org.springframework.boot.loader.tools.LibraryScope;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -56,9 +57,11 @@ import static org.mockito.Mockito.times;
 class ArtifactsLibrariesTests {
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Artifact artifact;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ArtifactHandler artifactHandler;
 
 	private Set<Artifact> artifacts;
@@ -68,9 +71,11 @@ class ArtifactsLibrariesTests {
 	private ArtifactsLibraries libs;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private LibraryCallback callback;
 
 	@Captor
+	@SuppressWarnings("NullAway.Init")
 	private ArgumentCaptor<Library> libraryCaptor;
 
 	@BeforeEach
@@ -146,7 +151,9 @@ class ArtifactsLibrariesTests {
 			.doWithLibraries((library) -> {
 				assertThat(library.isIncluded()).isTrue();
 				assertThat(library.isLocal()).isFalse();
-				assertThat(library.getCoordinates().getVersion()).isEqualTo("1.0-SNAPSHOT");
+				LibraryCoordinates coordinates = library.getCoordinates();
+				assertThat(coordinates).isNotNull();
+				assertThat(coordinates.getVersion()).isEqualTo("1.0-SNAPSHOT");
 			});
 	}
 

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/ClassPathTests.java

@@ -24,6 +24,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.UnaryOperator;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
@@ -93,11 +94,11 @@ class ClassPathTests {
 		assertThat(classPath.toString()).isEqualTo(path1 + File.pathSeparator + path2);
 	}
 
-	private UnaryOperator<String> onWindows() {
+	private UnaryOperator<@Nullable String> onWindows() {
 		return Map.of("os.name", "windows")::get;
 	}
 
-	private UnaryOperator<String> onLinux() {
+	private UnaryOperator<@Nullable String> onLinux() {
 		return Map.of("os.name", "linux")::get;
 	}
 

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/CustomLayersProviderTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.maven;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.w3c.dom.Document;
@@ -69,7 +70,7 @@ class CustomLayersProviderTests {
 		assertThat(layers.getLayer("test")).hasToString("application");
 	}
 
-	private Library mockLibrary(String name, String groupId, String version) {
+	private Library mockLibrary(String name, String groupId, @Nullable String version) {
 		Library library = mock(Library.class);
 		given(library.getName()).willReturn(name);
 		given(library.getCoordinates()).willReturn(LibraryCoordinates.of(groupId, null, version));

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/DependencyFilterMojoTests.java

@@ -33,6 +33,7 @@ import org.apache.maven.artifact.Artifact;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.shared.artifact.filter.collection.ArtifactsFilter;
 import org.apache.maven.shared.artifact.filter.collection.ScopeFilter;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
@@ -48,6 +49,7 @@ import static org.mockito.Mockito.mock;
 class DependencyFilterMojoTests {
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	static Path temp;
 
 	@Test
@@ -121,11 +123,12 @@ class DependencyFilterMojoTests {
 		return createArtifact(groupId, artifactId, null);
 	}
 
-	private static Artifact createArtifact(String groupId, String artifactId, String scope) {
+	private static Artifact createArtifact(String groupId, String artifactId, @Nullable String scope) {
 		return createArtifact(groupId, artifactId, scope, null);
 	}
 
-	private static Artifact createArtifact(String groupId, String artifactId, String scope, String jarType) {
+	private static Artifact createArtifact(String groupId, String artifactId, @Nullable String scope,
+			@Nullable String jarType) {
 		Artifact a = mock(Artifact.class);
 		given(a.getGroupId()).willReturn(groupId);
 		given(a.getArtifactId()).willReturn(artifactId);
@@ -136,7 +139,7 @@ class DependencyFilterMojoTests {
 		return a;
 	}
 
-	private static File createArtifactFile(String jarType) {
+	private static File createArtifactFile(@Nullable String jarType) {
 		Path jarPath = temp.resolve(UUID.randomUUID() + ".jar");
 		Manifest manifest = new Manifest();
 		manifest.getMainAttributes().putValue("Manifest-Version", "1.0");

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/DockerTests.java

@@ -24,6 +24,7 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.buildpack.platform.build.BuilderDockerConfiguration;
 import org.springframework.boot.buildpack.platform.docker.configuration.DockerConnectionConfiguration;
+import org.springframework.boot.buildpack.platform.docker.configuration.DockerRegistryAuthentication;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
@@ -43,9 +44,16 @@ class DockerTests {
 		Docker docker = new Docker();
 		BuilderDockerConfiguration dockerConfiguration = createDockerConfiguration(docker);
 		assertThat(dockerConfiguration.connection()).isNull();
-		assertThat(dockerConfiguration.builderRegistryAuthentication().getAuthHeader()).isNull();
-		assertThat(decoded(dockerConfiguration.publishRegistryAuthentication().getAuthHeader()))
-			.contains("\"username\" : \"\"")
+		DockerRegistryAuthentication builderRegistryAuthentication = dockerConfiguration
+			.builderRegistryAuthentication();
+		assertThat(builderRegistryAuthentication).isNotNull();
+		assertThat(builderRegistryAuthentication.getAuthHeader()).isNull();
+		DockerRegistryAuthentication publishRegistryAuthentication = dockerConfiguration
+			.publishRegistryAuthentication();
+		assertThat(publishRegistryAuthentication).isNotNull();
+		String authHeader = publishRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"username\" : \"\"")
 			.contains("\"password\" : \"\"")
 			.contains("\"email\" : \"\"")
 			.contains("\"serveraddress\" : \"\"");
@@ -59,13 +67,21 @@ class DockerTests {
 		docker.setCertPath("/tmp/ca-cert");
 		BuilderDockerConfiguration dockerConfiguration = createDockerConfiguration(docker);
 		DockerConnectionConfiguration.Host host = (DockerConnectionConfiguration.Host) dockerConfiguration.connection();
+		assertThat(host).isNotNull();
 		assertThat(host.address()).isEqualTo("docker.example.com");
 		assertThat(host.secure()).isTrue();
 		assertThat(host.certificatePath()).isEqualTo("/tmp/ca-cert");
 		assertThat(dockerConfiguration.bindHostToBuilder()).isFalse();
-		assertThat(createDockerConfiguration(docker).builderRegistryAuthentication().getAuthHeader()).isNull();
-		assertThat(decoded(dockerConfiguration.publishRegistryAuthentication().getAuthHeader()))
-			.contains("\"username\" : \"\"")
+		DockerRegistryAuthentication builderRegistryAuthentication = createDockerConfiguration(docker)
+			.builderRegistryAuthentication();
+		assertThat(builderRegistryAuthentication).isNotNull();
+		assertThat(builderRegistryAuthentication.getAuthHeader()).isNull();
+		DockerRegistryAuthentication publishRegistryAuthentication = dockerConfiguration
+			.publishRegistryAuthentication();
+		assertThat(publishRegistryAuthentication).isNotNull();
+		String authHeader = publishRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"username\" : \"\"")
 			.contains("\"password\" : \"\"")
 			.contains("\"email\" : \"\"")
 			.contains("\"serveraddress\" : \"\"");
@@ -78,11 +94,19 @@ class DockerTests {
 		BuilderDockerConfiguration dockerConfiguration = createDockerConfiguration(docker);
 		DockerConnectionConfiguration.Context context = (DockerConnectionConfiguration.Context) dockerConfiguration
 			.connection();
+		assertThat(context).isNotNull();
 		assertThat(context.context()).isEqualTo("test-context");
 		assertThat(dockerConfiguration.bindHostToBuilder()).isFalse();
-		assertThat(createDockerConfiguration(docker).builderRegistryAuthentication().getAuthHeader()).isNull();
-		assertThat(decoded(dockerConfiguration.publishRegistryAuthentication().getAuthHeader()))
-			.contains("\"username\" : \"\"")
+		DockerRegistryAuthentication builderRegistryAuthentication = createDockerConfiguration(docker)
+			.builderRegistryAuthentication();
+		assertThat(builderRegistryAuthentication).isNotNull();
+		assertThat(builderRegistryAuthentication.getAuthHeader()).isNull();
+		DockerRegistryAuthentication publishRegistryAuthentication = dockerConfiguration
+			.publishRegistryAuthentication();
+		assertThat(publishRegistryAuthentication).isNotNull();
+		String authHeader = publishRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"username\" : \"\"")
 			.contains("\"password\" : \"\"")
 			.contains("\"email\" : \"\"")
 			.contains("\"serveraddress\" : \"\"");
@@ -106,13 +130,21 @@ class DockerTests {
 		docker.setBindHostToBuilder(true);
 		BuilderDockerConfiguration dockerConfiguration = createDockerConfiguration(docker);
 		DockerConnectionConfiguration.Host host = (DockerConnectionConfiguration.Host) dockerConfiguration.connection();
+		assertThat(host).isNotNull();
 		assertThat(host.address()).isEqualTo("docker.example.com");
 		assertThat(host.secure()).isTrue();
 		assertThat(host.certificatePath()).isEqualTo("/tmp/ca-cert");
 		assertThat(dockerConfiguration.bindHostToBuilder()).isTrue();
-		assertThat(createDockerConfiguration(docker).builderRegistryAuthentication().getAuthHeader()).isNull();
-		assertThat(decoded(dockerConfiguration.publishRegistryAuthentication().getAuthHeader()))
-			.contains("\"username\" : \"\"")
+		DockerRegistryAuthentication builderRegistryAuthentication = createDockerConfiguration(docker)
+			.builderRegistryAuthentication();
+		assertThat(builderRegistryAuthentication).isNotNull();
+		assertThat(builderRegistryAuthentication.getAuthHeader()).isNull();
+		DockerRegistryAuthentication publishRegistryAuthentication = dockerConfiguration
+			.publishRegistryAuthentication();
+		assertThat(publishRegistryAuthentication).isNotNull();
+		String authHeader = publishRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"username\" : \"\"")
 			.contains("\"password\" : \"\"")
 			.contains("\"email\" : \"\"")
 			.contains("\"serveraddress\" : \"\"");
@@ -126,13 +158,21 @@ class DockerTests {
 		docker.setPublishRegistry(
 				new Docker.DockerRegistry("user2", "secret2", "https://docker2.example.com", "docker2@example.com"));
 		BuilderDockerConfiguration dockerConfiguration = createDockerConfiguration(docker);
-		assertThat(decoded(dockerConfiguration.builderRegistryAuthentication().getAuthHeader()))
-			.contains("\"username\" : \"user1\"")
+		DockerRegistryAuthentication builderRegistryAuthentication = dockerConfiguration
+			.builderRegistryAuthentication();
+		assertThat(builderRegistryAuthentication).isNotNull();
+		String authHeader = builderRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"username\" : \"user1\"")
 			.contains("\"password\" : \"secret1\"")
 			.contains("\"email\" : \"docker1@example.com\"")
 			.contains("\"serveraddress\" : \"https://docker1.example.com\"");
-		assertThat(decoded(dockerConfiguration.publishRegistryAuthentication().getAuthHeader()))
-			.contains("\"username\" : \"user2\"")
+		DockerRegistryAuthentication publishRegistryAuthentication = dockerConfiguration
+			.publishRegistryAuthentication();
+		assertThat(publishRegistryAuthentication).isNotNull();
+		authHeader = publishRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"username\" : \"user2\"")
 			.contains("\"password\" : \"secret2\"")
 			.contains("\"email\" : \"docker2@example.com\"")
 			.contains("\"serveraddress\" : \"https://docker2.example.com\"");
@@ -171,10 +211,18 @@ class DockerTests {
 		docker.setBuilderRegistry(new Docker.DockerRegistry("token1"));
 		docker.setPublishRegistry(new Docker.DockerRegistry("token2"));
 		BuilderDockerConfiguration dockerConfiguration = createDockerConfiguration(docker);
-		assertThat(decoded(dockerConfiguration.builderRegistryAuthentication().getAuthHeader()))
-			.contains("\"identitytoken\" : \"token1\"");
-		assertThat(decoded(dockerConfiguration.publishRegistryAuthentication().getAuthHeader()))
-			.contains("\"identitytoken\" : \"token2\"");
+		DockerRegistryAuthentication builderRegistryAuthentication = dockerConfiguration
+			.builderRegistryAuthentication();
+		assertThat(builderRegistryAuthentication).isNotNull();
+		String authHeader = builderRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"identitytoken\" : \"token1\"");
+		DockerRegistryAuthentication publishRegistryAuthentication = dockerConfiguration
+			.publishRegistryAuthentication();
+		assertThat(publishRegistryAuthentication).isNotNull();
+		authHeader = publishRegistryAuthentication.getAuthHeader();
+		assertThat(authHeader).isNotNull();
+		assertThat(decoded(authHeader)).contains("\"identitytoken\" : \"token2\"");
 	}
 
 	@Test

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/ExcludeFilterTests.java

@@ -23,6 +23,7 @@ import java.util.Set;
 
 import org.apache.maven.artifact.Artifact;
 import org.apache.maven.shared.artifact.filter.collection.ArtifactFilterException;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -106,7 +107,7 @@ class ExcludeFilterTests {
 		return createExclude(groupId, artifactId, null);
 	}
 
-	private Exclude createExclude(String groupId, String artifactId, String classifier) {
+	private Exclude createExclude(String groupId, String artifactId, @Nullable String classifier) {
 		Exclude exclude = new Exclude();
 		exclude.setGroupId(groupId);
 		exclude.setArtifactId(artifactId);
@@ -116,7 +117,7 @@ class ExcludeFilterTests {
 		return exclude;
 	}
 
-	private Artifact createArtifact(String groupId, String artifactId, String classifier) {
+	private Artifact createArtifact(String groupId, String artifactId, @Nullable String classifier) {
 		Artifact a = mock(Artifact.class);
 		given(a.getGroupId()).willReturn(groupId);
 		given(a.getArtifactId()).willReturn(artifactId);

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/ImageTests.java

@@ -41,6 +41,7 @@ import org.springframework.boot.maven.CacheInfo.VolumeCacheInfo;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link Image}.
@@ -305,7 +306,7 @@ class ImageTests {
 	}
 
 	private Function<Owner, TarArchive> mockApplicationContent() {
-		return (owner) -> null;
+		return (owner) -> mock(TarArchive.class);
 	}
 
 }

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/IncludeFilterTests.java

@@ -23,6 +23,7 @@ import java.util.Set;
 
 import org.apache.maven.artifact.Artifact;
 import org.apache.maven.shared.artifact.filter.collection.ArtifactFilterException;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -104,7 +105,7 @@ class IncludeFilterTests {
 		return createInclude(groupId, artifactId, null);
 	}
 
-	private Include createInclude(String groupId, String artifactId, String classifier) {
+	private Include createInclude(String groupId, String artifactId, @Nullable String classifier) {
 		Include include = new Include();
 		include.setGroupId(groupId);
 		include.setArtifactId(artifactId);
@@ -114,7 +115,7 @@ class IncludeFilterTests {
 		return include;
 	}
 
-	private Artifact createArtifact(String groupId, String artifactId, String classifier) {
+	private Artifact createArtifact(String groupId, String artifactId, @Nullable String classifier) {
 		Artifact a = mock(Artifact.class);
 		given(a.getGroupId()).willReturn(groupId);
 		given(a.getArtifactId()).willReturn(artifactId);

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/JarTypeFilterTests.java

@@ -23,6 +23,7 @@ import java.util.jar.JarOutputStream;
 import java.util.jar.Manifest;
 
 import org.apache.maven.artifact.Artifact;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
@@ -38,6 +39,7 @@ import static org.mockito.Mockito.mock;
 class JarTypeFilterTests {
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	Path temp;
 
 	@Test
@@ -70,7 +72,7 @@ class JarTypeFilterTests {
 		assertThat(new JarTypeFilter().filter(createArtifactWithNoManifest())).isFalse();
 	}
 
-	private Artifact createArtifact(String springBootJarType) {
+	private Artifact createArtifact(@Nullable String springBootJarType) {
 		Path jarPath = this.temp.resolve("test.jar");
 		Manifest manifest = new Manifest();
 		manifest.getMainAttributes().putValue("Manifest-Version", "1.0");

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/MavenBuildOutputTimestampTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.maven;
 import java.nio.file.attribute.FileTime;
 import java.time.Instant;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -88,11 +89,11 @@ class MavenBuildOutputTimestampTests {
 		assertThat(parseFileTime("2019-10-05T14:37:42Z")).isEqualTo(FileTime.fromMillis(1570286262000L));
 	}
 
-	private static Instant parse(String timestamp) {
+	private static @Nullable Instant parse(@Nullable String timestamp) {
 		return new MavenBuildOutputTimestamp(timestamp).toInstant();
 	}
 
-	private static FileTime parseFileTime(String timestamp) {
+	private static @Nullable FileTime parseFileTime(@Nullable String timestamp) {
 		return new MavenBuildOutputTimestamp(timestamp).toFileTime();
 	}
 

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/PropertiesMergingResourceTransformerTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.maven;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.jar.JarEntry;
 import java.util.jar.JarInputStream;
@@ -40,14 +41,17 @@ class PropertiesMergingResourceTransformerTests {
 	@Test
 	void testProcess() throws Exception {
 		assertThat(this.transformer.hasTransformedResource()).isFalse();
-		this.transformer.processResource("foo", new ByteArrayInputStream("foo=bar".getBytes()), null, 0);
+		this.transformer.processResource("foo", new ByteArrayInputStream("foo=bar".getBytes()), Collections.emptyList(),
+				0);
 		assertThat(this.transformer.hasTransformedResource()).isTrue();
 	}
 
 	@Test
 	void testMerge() throws Exception {
-		this.transformer.processResource("foo", new ByteArrayInputStream("foo=bar".getBytes()), null, 0);
-		this.transformer.processResource("bar", new ByteArrayInputStream("foo=spam".getBytes()), null, 0);
+		this.transformer.processResource("foo", new ByteArrayInputStream("foo=bar".getBytes()), Collections.emptyList(),
+				0);
+		this.transformer.processResource("bar", new ByteArrayInputStream("foo=spam".getBytes()),
+				Collections.emptyList(), 0);
 		assertThat(this.transformer.getData().getProperty("foo")).isEqualTo("bar,spam");
 	}
 
@@ -55,7 +59,8 @@ class PropertiesMergingResourceTransformerTests {
 	void testOutput() throws Exception {
 		this.transformer.setResource("foo");
 		long time = 1592911068000L;
-		this.transformer.processResource("foo", new ByteArrayInputStream("foo=bar".getBytes()), null, time);
+		this.transformer.processResource("foo", new ByteArrayInputStream("foo=bar".getBytes()), Collections.emptyList(),
+				time);
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
 		JarOutputStream os = new JarOutputStream(out);
 		this.transformer.modifyOutputStream(os);

build-plugin/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/RunArgumentsTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.maven;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -35,6 +36,7 @@ class RunArgumentsTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Maven can't handle nullable arrays
 	void parseNullArray() {
 		String[] args = new RunArguments((String[]) null).asArray();
 		assertThat(args).isNotNull();
@@ -92,7 +94,7 @@ class RunArgumentsTests {
 		assertThat(args[0]).isEqualTo("-Dvalue=My Value");
 	}
 
-	private String[] parseArgs(String args) {
+	private String[] parseArgs(@Nullable String args) {
 		return new RunArguments(args).asArray();
 	}