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

See gh-46587

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractAotMojo.java

@@ -44,6 +44,7 @@ import org.apache.maven.plugin.MojoFailureException;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.shared.artifact.filter.collection.ArtifactsFilter;
 import org.apache.maven.toolchain.ToolchainManager;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Abstract base class for AOT processing MOJOs.
@@ -59,6 +60,7 @@ public abstract class AbstractAotMojo extends AbstractDependencyFilterMojo {
 	 * The current Maven session. This is used for toolchain manager API calls.
 	 */
 	@Parameter(defaultValue = "${session}", readonly = true)
+	@SuppressWarnings("NullAway.Init")
 	private MavenSession session;
 
 	/**
@@ -76,21 +78,21 @@ public abstract class AbstractAotMojo extends AbstractDependencyFilterMojo {
 	 * List of JVM system properties to pass to the AOT process.
 	 */
 	@Parameter
-	private Map<String, String> systemPropertyVariables;
+	private @Nullable Map<String, String> systemPropertyVariables;
 
 	/**
 	 * JVM arguments that should be associated with the AOT process. On command line, make
 	 * sure to wrap multiple values between quotes.
 	 */
 	@Parameter(property = "spring-boot.aot.jvmArguments")
-	private String jvmArguments;
+	private @Nullable String jvmArguments;
 
 	/**
 	 * Arguments that should be provided to the AOT compile process. On command line, make
 	 * sure to wrap multiple values between quotes.
 	 */
 	@Parameter(property = "spring-boot.aot.compilerArguments")
-	private String compilerArguments;
+	private @Nullable String compilerArguments;
 
 	protected AbstractAotMojo(ToolchainManager toolchainManager) {
 		this.toolchainManager = toolchainManager;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractDependencyFilterMojo.java

@@ -36,6 +36,7 @@ import org.apache.maven.shared.artifact.filter.collection.AbstractArtifactFeatur
 import org.apache.maven.shared.artifact.filter.collection.ArtifactFilterException;
 import org.apache.maven.shared.artifact.filter.collection.ArtifactsFilter;
 import org.apache.maven.shared.artifact.filter.collection.FilterArtifacts;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A base mojo filtering the dependencies of the project.
@@ -67,6 +68,7 @@ public abstract class AbstractDependencyFilterMojo extends AbstractMojo {
 	 * @since 3.0.0
 	 */
 	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	protected MavenProject project;
 
 	/**
@@ -78,7 +80,7 @@ public abstract class AbstractDependencyFilterMojo extends AbstractMojo {
 	 * @since 1.2.0
 	 */
 	@Parameter(property = "spring-boot.includes")
-	private List<Include> includes;
+	private @Nullable List<Include> includes;
 
 	/**
 	 * Collection of artifact definitions to exclude. The {@link Exclude} element defines
@@ -89,20 +91,20 @@ public abstract class AbstractDependencyFilterMojo extends AbstractMojo {
 	 * @since 1.1.0
 	 */
 	@Parameter(property = "spring-boot.excludes")
-	private List<Exclude> excludes;
+	private @Nullable List<Exclude> excludes;
 
 	/**
 	 * Comma separated list of groupId names to exclude (exact match).
 	 * @since 1.1.0
 	 */
 	@Parameter(property = "spring-boot.excludeGroupIds", defaultValue = "")
-	private String excludeGroupIds;
+	private @Nullable String excludeGroupIds;
 
-	protected void setExcludes(List<Exclude> excludes) {
+	protected void setExcludes(@Nullable List<Exclude> excludes) {
 		this.excludes = excludes;
 	}
 
-	protected void setIncludes(List<Include> includes) {
+	protected void setIncludes(@Nullable List<Include> includes) {
 		this.includes = includes;
 	}
 
@@ -163,7 +165,7 @@ public abstract class AbstractDependencyFilterMojo extends AbstractMojo {
 		return filters;
 	}
 
-	private String cleanFilterConfig(String content) {
+	private String cleanFilterConfig(@Nullable String content) {
 		if (content == null || content.trim().isEmpty()) {
 			return "";
 		}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractPackagerMojo.java

@@ -36,6 +36,7 @@ import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.MavenProjectHelper;
 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.w3c.dom.Document;
 import org.xml.sax.InputSource;
 
@@ -67,6 +68,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @since 1.0.0
 	 */
 	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	protected MavenProject project;
 
 	/**
@@ -74,6 +76,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @since 2.4.0
 	 */
 	@Parameter(defaultValue = "${session}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	protected MavenSession session;
 
 	/**
@@ -88,7 +91,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @since 1.0.0
 	 */
 	@Parameter
-	private String mainClass;
+	private @Nullable String mainClass;
 
 	/**
 	 * Exclude Spring Boot devtools from the repackaged archive.
@@ -135,7 +138,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @return {@code null}, indicating a layout type will be chosen based on the original
 	 * archive type
 	 */
-	protected LayoutType getLayout() {
+	protected @Nullable LayoutType getLayout() {
 		return null;
 	}
 
@@ -144,7 +147,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @return the loader implementation or {@code null}
 	 * @since 3.2.0
 	 */
-	protected LoaderImplementation getLoaderImplementation() {
+	protected @Nullable LoaderImplementation getLoaderImplementation() {
 		return null;
 	}
 
@@ -153,7 +156,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * no explicit layout is set.
 	 * @return {@code null}, indicating a default layout factory will be chosen
 	 */
-	protected LayoutFactory getLayoutFactory() {
+	protected @Nullable LayoutFactory getLayoutFactory() {
 		return null;
 	}
 
@@ -211,7 +214,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @return the libraries to use
 	 * @throws MojoExecutionException on execution error
 	 */
-	protected final Libraries getLibraries(Collection<Dependency> unpacks) throws MojoExecutionException {
+	protected final Libraries getLibraries(@Nullable Collection<Dependency> unpacks) throws MojoExecutionException {
 		Set<Artifact> artifacts = this.project.getArtifacts();
 		Set<Artifact> includedArtifacts = filterDependencies(artifacts, getAdditionalFilters());
 		return new ArtifactsLibraries(artifacts, includedArtifacts, this.session.getProjects(), unpacks, getLog());
@@ -238,12 +241,12 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @param classifier the artifact classifier
 	 * @return the source artifact to repackage
 	 */
-	protected Artifact getSourceArtifact(String classifier) {
+	protected Artifact getSourceArtifact(@Nullable String classifier) {
 		Artifact sourceArtifact = getArtifact(classifier);
 		return (sourceArtifact != null) ? sourceArtifact : this.project.getArtifact();
 	}
 
-	private Artifact getArtifact(String classifier) {
+	private @Nullable Artifact getArtifact(@Nullable String classifier) {
 		if (classifier != null) {
 			for (Artifact attachedArtifact : this.project.getAttachedArtifacts()) {
 				if (classifier.equals(attachedArtifact.getClassifier()) && attachedArtifact.getFile() != null
@@ -255,7 +258,7 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 		return null;
 	}
 
-	protected File getTargetFile(String finalName, String classifier, File targetDirectory) {
+	protected File getTargetFile(String finalName, @Nullable String classifier, File targetDirectory) {
 		String classifierSuffix = (classifier != null) ? classifier.trim() : "";
 		if (!classifierSuffix.isEmpty() && !classifierSuffix.startsWith("-")) {
 			classifierSuffix = "-" + classifierSuffix;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractRunMojo.java

@@ -36,6 +36,7 @@ import org.apache.maven.plugin.MojoFailureException;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.toolchain.ToolchainManager;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.loader.tools.FileUtils;
 
@@ -60,6 +61,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	private MavenProject project;
 
 	/**
@@ -68,6 +70,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter(defaultValue = "${session}", readonly = true)
+	@SuppressWarnings("NullAway.Init")
 	private MavenSession session;
 
 	/**
@@ -95,6 +98,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 2.2.0
 	 */
 	@Parameter(property = "spring-boot.run.agents")
+	@SuppressWarnings("NullAway") // maven-maven-plugin can't handle annotated arrays
 	private File[] agents;
 
 	/**
@@ -112,7 +116,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.5.0
 	 */
 	@Parameter(property = "spring-boot.run.workingDirectory")
-	private File workingDirectory;
+	private @Nullable File workingDirectory;
 
 	/**
 	 * JVM arguments that should be associated with the forked process used to run the
@@ -121,7 +125,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.1.0
 	 */
 	@Parameter(property = "spring-boot.run.jvmArguments")
-	private String jvmArguments;
+	private @Nullable String jvmArguments;
 
 	/**
 	 * List of JVM system properties to pass to the process.
@@ -129,7 +133,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 2.1.0
 	 */
 	@Parameter
-	private Map<String, String> systemPropertyVariables;
+	private @Nullable Map<String, String> systemPropertyVariables;
 
 	/**
 	 * List of Environment variables that should be associated with the forked process
@@ -138,7 +142,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 2.1.0
 	 */
 	@Parameter
-	private Map<String, String> environmentVariables;
+	private @Nullable Map<String, String> environmentVariables;
 
 	/**
 	 * Arguments that should be passed to the application.
@@ -146,6 +150,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter
+	@SuppressWarnings("NullAway") // maven-maven-plugin can't handle annotated arrays
 	private String[] arguments;
 
 	/**
@@ -156,7 +161,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 2.2.3
 	 */
 	@Parameter(property = "spring-boot.run.arguments")
-	private String commandlineArguments;
+	private @Nullable String commandlineArguments;
 
 	/**
 	 * The spring profiles to activate. Convenience shortcut of specifying the
@@ -166,6 +171,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.3.0
 	 */
 	@Parameter(property = "spring-boot.run.profiles")
+	@SuppressWarnings("NullAway") // maven-maven-plugin can't handle annotated arrays
 	private String[] profiles;
 
 	/**
@@ -175,7 +181,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter(property = "spring-boot.run.main-class")
-	private String mainClass;
+	private @Nullable String mainClass;
 
 	/**
 	 * Additional classpath elements that should be added to the classpath. An element can
@@ -184,6 +190,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 3.2.0
 	 */
 	@Parameter(property = "spring-boot.run.additional-classpath-elements")
+	@SuppressWarnings("NullAway") // maven-maven-plugin can't handle annotated arrays
 	private String[] additionalClasspathElements;
 
 	/**
@@ -193,6 +200,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter(defaultValue = "${project.build.outputDirectory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File classesDirectory;
 
 	/**
@@ -336,7 +344,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	}
 
 	private void addActiveProfileArgument(RunArguments arguments) {
-		if (this.profiles.length > 0) {
+		if (this.profiles != null && this.profiles.length > 0) {
 			StringBuilder arg = new StringBuilder("--spring.profiles.active=");
 			for (int i = 0; i < this.profiles.length; i++) {
 				arg.append(this.profiles[i]);
@@ -424,7 +432,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 */
 	static class SystemPropertyFormatter {
 
-		static String format(String key, String value) {
+		static String format(@Nullable String key, @Nullable String value) {
 			if (key == null) {
 				return "";
 			}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/ArtifactsLibraries.java

@@ -29,6 +29,7 @@ import org.apache.maven.artifact.Artifact;
 import org.apache.maven.model.Dependency;
 import org.apache.maven.plugin.logging.Log;
 import org.apache.maven.project.MavenProject;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.loader.tools.Libraries;
 import org.springframework.boot.loader.tools.Library;
@@ -64,7 +65,7 @@ public class ArtifactsLibraries implements Libraries {
 
 	private final Collection<MavenProject> localProjects;
 
-	private final Collection<Dependency> unpacks;
+	private final @Nullable Collection<Dependency> unpacks;
 
 	private final Log log;
 
@@ -93,7 +94,7 @@ public class ArtifactsLibraries implements Libraries {
 	 * @since 2.4.8
 	 */
 	public ArtifactsLibraries(Set<Artifact> artifacts, Set<Artifact> includedArtifacts,
-			Collection<MavenProject> localProjects, Collection<Dependency> unpacks, Log log) {
+			Collection<MavenProject> localProjects, @Nullable Collection<Dependency> unpacks, Log log) {
 		this.artifacts = artifacts;
 		this.includedArtifacts = includedArtifacts;
 		this.localProjects = localProjects;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/BuildImageMojo.java

@@ -34,6 +34,7 @@ import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugin.logging.Log;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.project.MavenProjectHelper;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.buildpack.platform.build.AbstractBuildLog;
 import org.springframework.boot.buildpack.platform.build.BuildLog;
@@ -71,13 +72,15 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter(defaultValue = "${project.build.directory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File sourceDirectory;
 
 	/**
 	 * Name of the source archive.
 	 * @since 2.3.0
 	 */
-	@Parameter(defaultValue = "${project.build.finalName}", readonly = true)
+	@Parameter(defaultValue = "${project.build.finalName}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	private String finalName;
 
 	/**
@@ -92,7 +95,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter
-	private String classifier;
+	private @Nullable String classifier;
 
 	/**
 	 * Image configuration, with {@code builder}, {@code runImage}, {@code name},
@@ -101,7 +104,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter
-	private Image image;
+	private @Nullable Image image;
 
 	/**
 	 * Alias for {@link Image#name} to support configuration through command-line
@@ -109,7 +112,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter(property = "spring-boot.build-image.imageName")
-	String imageName;
+	@Nullable String imageName;
 
 	/**
 	 * Alias for {@link Image#builder} to support configuration through command-line
@@ -117,14 +120,14 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter(property = "spring-boot.build-image.builder")
-	String imageBuilder;
+	@Nullable String imageBuilder;
 
 	/**
 	 * Alias for {@link Image#trustBuilder} to support configuration through command-line
 	 * property.
 	 */
 	@Parameter(property = "spring-boot.build-image.trustBuilder")
-	Boolean trustBuilder;
+	@Nullable Boolean trustBuilder;
 
 	/**
 	 * Alias for {@link Image#runImage} to support configuration through command-line
@@ -132,7 +135,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.1
 	 */
 	@Parameter(property = "spring-boot.build-image.runImage")
-	String runImage;
+	@Nullable String runImage;
 
 	/**
 	 * Alias for {@link Image#cleanCache} to support configuration through command-line
@@ -140,21 +143,21 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.4.0
 	 */
 	@Parameter(property = "spring-boot.build-image.cleanCache")
-	Boolean cleanCache;
+	@Nullable Boolean cleanCache;
 
 	/**
 	 * Alias for {@link Image#pullPolicy} to support configuration through command-line
 	 * property.
 	 */
 	@Parameter(property = "spring-boot.build-image.pullPolicy")
-	PullPolicy pullPolicy;
+	@Nullable PullPolicy pullPolicy;
 
 	/**
 	 * Alias for {@link Image#publish} to support configuration through command-line
 	 * property.
 	 */
 	@Parameter(property = "spring-boot.build-image.publish")
-	Boolean publish;
+	@Nullable Boolean publish;
 
 	/**
 	 * Alias for {@link Image#network} to support configuration through command-line
@@ -162,7 +165,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.6.0
 	 */
 	@Parameter(property = "spring-boot.build-image.network")
-	String network;
+	@Nullable String network;
 
 	/**
 	 * Alias for {@link Image#createdDate} to support configuration through command-line
@@ -170,7 +173,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 3.1.0
 	 */
 	@Parameter(property = "spring-boot.build-image.createdDate")
-	String createdDate;
+	@Nullable String createdDate;
 
 	/**
 	 * Alias for {@link Image#applicationDirectory} to support configuration through
@@ -178,7 +181,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 3.1.0
 	 */
 	@Parameter(property = "spring-boot.build-image.applicationDirectory")
-	String applicationDirectory;
+	@Nullable String applicationDirectory;
 
 	/**
 	 * Alias for {@link Image#imagePlatform} to support configuration through command-line
@@ -186,14 +189,14 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 3.4.0
 	 */
 	@Parameter(property = "spring-boot.build-image.imagePlatform")
-	String imagePlatform;
+	@Nullable String imagePlatform;
 
 	/**
 	 * Docker configuration options.
 	 * @since 2.4.0
 	 */
 	@Parameter
-	private Docker docker;
+	private @Nullable Docker docker;
 
 	/**
 	 * The type of archive (which corresponds to how the dependencies are laid out inside
@@ -202,14 +205,14 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.11
 	 */
 	@Parameter
-	private LayoutType layout;
+	private @Nullable LayoutType layout;
 
 	/**
 	 * The loader implementation that should be used.
 	 * @since 3.2.0
 	 */
 	@Parameter
-	private LoaderImplementation loaderImplementation;
+	private @Nullable LoaderImplementation loaderImplementation;
 
 	/**
 	 * The layout factory that will be used to create the executable archive if no
@@ -218,7 +221,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.11
 	 */
 	@Parameter
-	private LayoutFactory layoutFactory;
+	private @Nullable LayoutFactory layoutFactory;
 
 	protected BuildImageMojo(MavenProjectHelper projectHelper) {
 		super(projectHelper);
@@ -230,12 +233,12 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * is not provided
 	 */
 	@Override
-	protected LayoutType getLayout() {
+	protected @Nullable LayoutType getLayout() {
 		return this.layout;
 	}
 
 	@Override
-	protected LoaderImplementation getLoaderImplementation() {
+	protected @Nullable LoaderImplementation getLoaderImplementation() {
 		return this.loaderImplementation;
 	}
 
@@ -246,7 +249,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * parameter is not provided
 	 */
 	@Override
-	protected LayoutFactory getLayoutFactory() {
+	protected @Nullable LayoutFactory getLayoutFactory() {
 		return this.layoutFactory;
 	}
 
@@ -340,7 +343,7 @@ public abstract class BuildImageMojo extends AbstractPackagerMojo {
 	 * Return the {@link File} to use to back up the original source.
 	 * @return the file to use to back up the original source
 	 */
-	private File getBackupFile() {
+	private @Nullable File getBackupFile() {
 		// We can't use 'project.getAttachedArtifacts()' because package can be done in a
 		// forked lifecycle and will be null
 		if (this.classifier != null) {

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/BuildInfoMojo.java

@@ -33,6 +33,7 @@ import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.project.MavenProject;
+import org.jspecify.annotations.Nullable;
 import org.sonatype.plexus.build.incremental.BuildContext;
 
 import org.springframework.boot.loader.tools.BuildPropertiesWriter;
@@ -56,18 +57,21 @@ public class BuildInfoMojo extends AbstractMojo {
 	 * The Maven session.
 	 */
 	@Parameter(defaultValue = "${session}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	private MavenSession session;
 
 	/**
 	 * The Maven project.
 	 */
 	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	private MavenProject project;
 
 	/**
 	 * The location of the generated {@code build-info.properties} file.
 	 */
 	@Parameter(defaultValue = "${project.build.outputDirectory}/META-INF/build-info.properties")
+	@SuppressWarnings("NullAway.Init")
 	private File outputFile;
 
 	/**
@@ -79,14 +83,14 @@ public class BuildInfoMojo extends AbstractMojo {
 	 * @since 2.2.0
 	 */
 	@Parameter(defaultValue = "${project.build.outputTimestamp}")
-	private String time;
+	private @Nullable String time;
 
 	/**
 	 * Additional properties to store in the {@code build-info.properties} file. Each
 	 * entry is prefixed by {@code build.} in the generated {@code build-info.properties}.
 	 */
 	@Parameter
-	private Map<String, String> additionalProperties;
+	private @Nullable Map<String, String> additionalProperties;
 
 	/**
 	 * Properties that should be excluded {@code build-info.properties} file. Can be used
@@ -95,7 +99,7 @@ public class BuildInfoMojo extends AbstractMojo {
 	 * {@code additionalProperties}.
 	 */
 	@Parameter
-	private List<String> excludeInfoProperties;
+	private @Nullable List<String> excludeInfoProperties;
 
 	/**
 	 * Skip the execution.
@@ -138,11 +142,11 @@ public class BuildInfoMojo extends AbstractMojo {
 		return new ProjectDetails(group, artifact, version, name, time, additionalProperties);
 	}
 
-	private <T> T getIfNotExcluded(String name, T value) {
+	private <T> @Nullable T getIfNotExcluded(String name, @Nullable T value) {
 		return (this.excludeInfoProperties == null || !this.excludeInfoProperties.contains(name)) ? value : null;
 	}
 
-	private Map<String, String> applyExclusions(Map<String, String> source) {
+	private @Nullable Map<String, String> applyExclusions(@Nullable Map<String, String> source) {
 		if (source == null || this.excludeInfoProperties == null) {
 			return source;
 		}
@@ -151,7 +155,7 @@ public class BuildInfoMojo extends AbstractMojo {
 		return result;
 	}
 
-	private Instant getBuildTime() {
+	private @Nullable Instant getBuildTime() {
 		if (this.time == null || this.time.isEmpty()) {
 			Date startTime = this.session.getRequest().getStartTime();
 			return (startTime != null) ? startTime.toInstant() : Instant.now();

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/CacheInfo.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.maven;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.buildpack.platform.build.Cache;
 import org.springframework.util.Assert;
 
@@ -27,7 +29,7 @@ import org.springframework.util.Assert;
  */
 public class CacheInfo {
 
-	private Cache cache;
+	private @Nullable Cache cache;
 
 	public CacheInfo() {
 	}
@@ -38,24 +40,32 @@ public class CacheInfo {
 
 	public void setVolume(VolumeCacheInfo info) {
 		Assert.state(this.cache == null, "Each image building cache can be configured only once");
-		this.cache = Cache.volume(info.getName());
+		String name = info.getName();
+		Assert.state(name != null, "'name' must not be null");
+		this.cache = Cache.volume(name);
 	}
 
 	public void setBind(BindCacheInfo info) {
 		Assert.state(this.cache == null, "Each image building cache can be configured only once");
-		this.cache = Cache.bind(info.getSource());
+		String source = info.getSource();
+		Assert.state(source != null, "'source' must not be null");
+		this.cache = Cache.bind(source);
 	}
 
-	Cache asCache() {
+	@Nullable Cache asCache() {
 		return this.cache;
 	}
 
 	static CacheInfo fromVolume(VolumeCacheInfo cacheInfo) {
-		return new CacheInfo(Cache.volume(cacheInfo.getName()));
+		String name = cacheInfo.getName();
+		Assert.state(name != null, "'name' must not be null");
+		return new CacheInfo(Cache.volume(name));
 	}
 
 	static CacheInfo fromBind(BindCacheInfo cacheInfo) {
-		return new CacheInfo(Cache.bind(cacheInfo.getSource()));
+		String source = cacheInfo.getSource();
+		Assert.state(source != null, "'source' must not be null");
+		return new CacheInfo(Cache.bind(source));
 	}
 
 	/**
@@ -63,7 +73,7 @@ public class CacheInfo {
 	 */
 	public static class VolumeCacheInfo {
 
-		private String name;
+		private @Nullable String name;
 
 		public VolumeCacheInfo() {
 		}
@@ -72,11 +82,11 @@ public class CacheInfo {
 			this.name = name;
 		}
 
-		public String getName() {
+		public @Nullable String getName() {
 			return this.name;
 		}
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 		}
 
@@ -87,7 +97,7 @@ public class CacheInfo {
 	 */
 	public static class BindCacheInfo {
 
-		private String source;
+		private @Nullable String source;
 
 		public BindCacheInfo() {
 		}
@@ -96,11 +106,11 @@ public class CacheInfo {
 			this.source = name;
 		}
 
-		public String getSource() {
+		public @Nullable String getSource() {
 			return this.source;
 		}
 
-		void setSource(String source) {
+		void setSource(@Nullable String source) {
 			this.source = source;
 		}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/CommandLineBuilder.java

@@ -23,6 +23,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Helper class to build the command-line arguments of a java process.
  *
@@ -53,7 +55,7 @@ final class CommandLineBuilder {
 		return this;
 	}
 
-	CommandLineBuilder withSystemProperties(Map<String, String> systemProperties) {
+	CommandLineBuilder withSystemProperties(@Nullable Map<String, String> systemProperties) {
 		if (systemProperties != null) {
 			systemProperties.entrySet()
 				.stream()
@@ -93,7 +95,7 @@ final class CommandLineBuilder {
 	 */
 	private static final class SystemPropertyFormatter {
 
-		static String format(String key, String value) {
+		static String format(@Nullable String key, @Nullable String value) {
 			if (key == null) {
 				return "";
 			}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/CustomLayersProvider.java

@@ -29,6 +29,7 @@ import javax.xml.validation.Schema;
 import javax.xml.validation.SchemaFactory;
 import javax.xml.validation.Validator;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -157,7 +158,7 @@ class CustomLayersProvider {
 		return patterns;
 	}
 
-	private Element getChildElement(Element element, String tagName) {
+	private @Nullable Element getChildElement(Element element, String tagName) {
 		NodeList nodes = element.getElementsByTagName(tagName);
 		if (nodes.getLength() == 0) {
 			return null;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/Docker.java

@@ -17,9 +17,11 @@
 package org.springframework.boot.maven;
 
 import org.apache.maven.plugin.logging.Log;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.buildpack.platform.build.BuilderDockerConfiguration;
 import org.springframework.boot.buildpack.platform.docker.configuration.DockerRegistryAuthentication;
+import org.springframework.util.Assert;
 
 /**
  * Docker configuration options.
@@ -30,29 +32,29 @@ import org.springframework.boot.buildpack.platform.docker.configuration.DockerRe
  */
 public class Docker {
 
-	private String host;
+	private @Nullable String host;
 
-	private String context;
+	private @Nullable String context;
 
 	private boolean tlsVerify;
 
-	private String certPath;
+	private @Nullable String certPath;
 
 	private boolean bindHostToBuilder;
 
-	private DockerRegistry builderRegistry;
+	private @Nullable DockerRegistry builderRegistry;
 
-	private DockerRegistry publishRegistry;
+	private @Nullable DockerRegistry publishRegistry;
 
 	/**
 	 * The host address of the Docker daemon.
 	 * @return the Docker host
 	 */
-	public String getHost() {
+	public @Nullable String getHost() {
 		return this.host;
 	}
 
-	void setHost(String host) {
+	void setHost(@Nullable String host) {
 		this.host = host;
 	}
 
@@ -60,11 +62,11 @@ public class Docker {
 	 * The Docker context to use to retrieve host configuration.
 	 * @return the Docker context
 	 */
-	public String getContext() {
+	public @Nullable String getContext() {
 		return this.context;
 	}
 
-	public void setContext(String context) {
+	public void setContext(@Nullable String context) {
 		this.context = context;
 	}
 
@@ -85,11 +87,11 @@ public class Docker {
 	 * Docker daemon.
 	 * @return the TLS certificate path
 	 */
-	public String getCertPath() {
+	public @Nullable String getCertPath() {
 		return this.certPath;
 	}
 
-	void setCertPath(String certPath) {
+	void setCertPath(@Nullable String certPath) {
 		this.certPath = certPath;
 	}
 
@@ -109,7 +111,7 @@ public class Docker {
 	 * Configuration of the Docker registry where builder and run images are stored.
 	 * @return the registry configuration
 	 */
-	DockerRegistry getBuilderRegistry() {
+	@Nullable DockerRegistry getBuilderRegistry() {
 		return this.builderRegistry;
 	}
 
@@ -118,7 +120,7 @@ public class Docker {
 	 * registry.
 	 * @param builderRegistry the registry configuration
 	 */
-	void setBuilderRegistry(DockerRegistry builderRegistry) {
+	void setBuilderRegistry(@Nullable DockerRegistry builderRegistry) {
 		this.builderRegistry = builderRegistry;
 	}
 
@@ -126,7 +128,7 @@ public class Docker {
 	 * Configuration of the Docker registry where the generated image will be published.
 	 * @return the registry configuration
 	 */
-	DockerRegistry getPublishRegistry() {
+	@Nullable DockerRegistry getPublishRegistry() {
 		return this.publishRegistry;
 	}
 
@@ -135,7 +137,7 @@ public class Docker {
 	 * registry.
 	 * @param builderRegistry the registry configuration
 	 */
-	void setPublishRegistry(DockerRegistry builderRegistry) {
+	void setPublishRegistry(@Nullable DockerRegistry builderRegistry) {
 		this.publishRegistry = builderRegistry;
 	}
 
@@ -189,17 +191,22 @@ public class Docker {
 				getRegistryAuthentication("publish", this.publishRegistry, authentication));
 	}
 
-	private DockerRegistryAuthentication getRegistryAuthentication(String type, DockerRegistry registry,
+	private DockerRegistryAuthentication getRegistryAuthentication(String type, @Nullable DockerRegistry registry,
 			DockerRegistryAuthentication fallback) {
 		if (registry == null || registry.isEmpty()) {
 			return fallback;
 		}
 		if (registry.hasTokenAuth() && !registry.hasUserAuth()) {
-			return DockerRegistryAuthentication.token(registry.getToken());
+			String token = registry.getToken();
+			Assert.state(token != null, "'token' must not be null");
+			return DockerRegistryAuthentication.token(token);
 		}
 		if (registry.hasUserAuth() && !registry.hasTokenAuth()) {
-			return DockerRegistryAuthentication.user(registry.getUsername(), registry.getPassword(), registry.getUrl(),
-					registry.getEmail());
+			String username = registry.getUsername();
+			String password = registry.getPassword();
+			Assert.state(username != null, "'username' must not be null");
+			Assert.state(password != null, "'password' must not be null");
+			return DockerRegistryAuthentication.user(username, password, registry.getUrl(), registry.getEmail());
 		}
 		throw new IllegalArgumentException("Invalid Docker " + type
 				+ " registry configuration, either token or username/password must be provided");
@@ -210,15 +217,15 @@ public class Docker {
 	 */
 	public static class DockerRegistry {
 
-		private String username;
+		private @Nullable String username;
 
-		private String password;
+		private @Nullable String password;
 
-		private String url;
+		private @Nullable String url;
 
-		private String email;
+		private @Nullable String email;
 
-		private String token;
+		private @Nullable String token;
 
 		public DockerRegistry() {
 		}
@@ -238,11 +245,11 @@ public class Docker {
 		 * The username that will be used for user authentication to the registry.
 		 * @return the username
 		 */
-		public String getUsername() {
+		public @Nullable String getUsername() {
 			return this.username;
 		}
 
-		void setUsername(String username) {
+		void setUsername(@Nullable String username) {
 			this.username = username;
 		}
 
@@ -250,11 +257,11 @@ public class Docker {
 		 * The password that will be used for user authentication to the registry.
 		 * @return the password
 		 */
-		public String getPassword() {
+		public @Nullable String getPassword() {
 			return this.password;
 		}
 
-		void setPassword(String password) {
+		void setPassword(@Nullable String password) {
 			this.password = password;
 		}
 
@@ -262,11 +269,11 @@ public class Docker {
 		 * The email address that will be used for user authentication to the registry.
 		 * @return the email address
 		 */
-		public String getEmail() {
+		public @Nullable String getEmail() {
 			return this.email;
 		}
 
-		void setEmail(String email) {
+		void setEmail(@Nullable String email) {
 			this.email = email;
 		}
 
@@ -274,11 +281,11 @@ public class Docker {
 		 * The URL of the registry.
 		 * @return the registry URL
 		 */
-		String getUrl() {
+		@Nullable String getUrl() {
 			return this.url;
 		}
 
-		void setUrl(String url) {
+		void setUrl(@Nullable String url) {
 			this.url = url;
 		}
 
@@ -286,11 +293,11 @@ public class Docker {
 		 * The token that will be used for token authentication to the registry.
 		 * @return the authentication token
 		 */
-		public String getToken() {
+		public @Nullable String getToken() {
 			return this.token;
 		}
 
-		void setToken(String token) {
+		void setToken(@Nullable String token) {
 			this.token = token;
 		}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/EnvVariables.java

@@ -22,6 +22,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Utility class for working with Env variables.
  *
@@ -31,11 +33,11 @@ class EnvVariables {
 
 	private final Map<String, String> variables;
 
-	EnvVariables(Map<String, String> variables) {
+	EnvVariables(@Nullable Map<String, String> variables) {
 		this.variables = parseEnvVariables(variables);
 	}
 
-	private static Map<String, String> parseEnvVariables(Map<String, String> args) {
+	private static Map<String, String> parseEnvVariables(@Nullable Map<String, String> args) {
 		if (args == null || args.isEmpty()) {
 			return Collections.emptyMap();
 		}
@@ -48,7 +50,7 @@ class EnvVariables {
 		return result;
 	}
 
-	private static String getValue(String value) {
+	private static String getValue(@Nullable String value) {
 		return (value != null) ? value : "";
 	}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/FilterableDependency.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.maven;
 
 import org.apache.maven.plugins.annotations.Parameter;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.Assert;
 
@@ -33,19 +34,21 @@ public abstract class FilterableDependency {
 	 * The groupId of the artifact to exclude.
 	 */
 	@Parameter(required = true)
+	@SuppressWarnings("NullAway.Init")
 	private String groupId;
 
 	/**
 	 * The artifactId of the artifact to exclude.
 	 */
 	@Parameter(required = true)
+	@SuppressWarnings("NullAway.Init")
 	private String artifactId;
 
 	/**
 	 * The classifier of the artifact to exclude.
 	 */
 	@Parameter
-	private String classifier;
+	private @Nullable String classifier;
 
 	String getGroupId() {
 		return this.groupId;
@@ -63,11 +66,11 @@ public abstract class FilterableDependency {
 		this.artifactId = artifactId;
 	}
 
-	String getClassifier() {
+	@Nullable String getClassifier() {
 		return this.classifier;
 	}
 
-	void setClassifier(String classifier) {
+	void setClassifier(@Nullable String classifier) {
 		this.classifier = classifier;
 	}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/Image.java

@@ -21,15 +21,18 @@ import java.util.Map;
 import java.util.function.Function;
 
 import org.apache.maven.artifact.Artifact;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
 import org.springframework.boot.buildpack.platform.build.BuildpackReference;
+import org.springframework.boot.buildpack.platform.build.Cache;
 import org.springframework.boot.buildpack.platform.build.PullPolicy;
 import org.springframework.boot.buildpack.platform.docker.type.Binding;
 import org.springframework.boot.buildpack.platform.docker.type.ImageName;
 import org.springframework.boot.buildpack.platform.docker.type.ImageReference;
 import org.springframework.boot.buildpack.platform.io.Owner;
 import org.springframework.boot.buildpack.platform.io.TarArchive;
+import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 
@@ -45,55 +48,55 @@ import org.springframework.util.StringUtils;
  */
 public class Image {
 
-	String name;
+	@Nullable String name;
 
-	String builder;
+	@Nullable String builder;
 
-	Boolean trustBuilder;
+	@Nullable Boolean trustBuilder;
 
-	String runImage;
+	@Nullable String runImage;
 
-	Map<String, String> env;
+	@Nullable Map<String, String> env;
 
-	Boolean cleanCache;
+	@Nullable Boolean cleanCache;
 
 	boolean verboseLogging;
 
-	PullPolicy pullPolicy;
+	@Nullable PullPolicy pullPolicy;
 
-	Boolean publish;
+	@Nullable Boolean publish;
 
-	List<String> buildpacks;
+	@Nullable List<String> buildpacks;
 
-	List<String> bindings;
+	@Nullable List<String> bindings;
 
-	String network;
+	@Nullable String network;
 
-	List<String> tags;
+	@Nullable List<String> tags;
 
-	CacheInfo buildWorkspace;
+	@Nullable CacheInfo buildWorkspace;
 
-	CacheInfo buildCache;
+	@Nullable CacheInfo buildCache;
 
-	CacheInfo launchCache;
+	@Nullable CacheInfo launchCache;
 
-	String createdDate;
+	@Nullable String createdDate;
 
-	String applicationDirectory;
+	@Nullable String applicationDirectory;
 
-	List<String> securityOptions;
+	@Nullable List<String> securityOptions;
 
-	String imagePlatform;
+	@Nullable String imagePlatform;
 
 	/**
 	 * The name of the created image.
 	 * @return the image name
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return this.name;
 	}
 
-	void setName(String name) {
+	void setName(@Nullable String name) {
 		this.name = name;
 	}
 
@@ -101,11 +104,11 @@ public class Image {
 	 * The name of the builder image to use to create the image.
 	 * @return the builder image name
 	 */
-	public String getBuilder() {
+	public @Nullable String getBuilder() {
 		return this.builder;
 	}
 
-	void setBuilder(String builder) {
+	void setBuilder(@Nullable String builder) {
 		this.builder = builder;
 	}
 
@@ -113,11 +116,11 @@ public class Image {
 	 * If the builder should be treated as trusted.
 	 * @return {@code true} if the builder should be treated as trusted
 	 */
-	public Boolean getTrustBuilder() {
+	public @Nullable Boolean getTrustBuilder() {
 		return this.trustBuilder;
 	}
 
-	void setTrustBuilder(Boolean trustBuilder) {
+	void setTrustBuilder(@Nullable Boolean trustBuilder) {
 		this.trustBuilder = trustBuilder;
 	}
 
@@ -125,11 +128,11 @@ public class Image {
 	 * The name of the run image to use to create the image.
 	 * @return the builder image name
 	 */
-	public String getRunImage() {
+	public @Nullable String getRunImage() {
 		return this.runImage;
 	}
 
-	void setRunImage(String runImage) {
+	void setRunImage(@Nullable String runImage) {
 		this.runImage = runImage;
 	}
 
@@ -137,7 +140,7 @@ public class Image {
 	 * Environment properties that should be passed to the builder.
 	 * @return the environment properties
 	 */
-	public Map<String, String> getEnv() {
+	public @Nullable Map<String, String> getEnv() {
 		return this.env;
 	}
 
@@ -145,11 +148,11 @@ public class Image {
 	 * If the cache should be cleaned before building.
 	 * @return {@code true} if the cache should be cleaned
 	 */
-	public Boolean getCleanCache() {
+	public @Nullable Boolean getCleanCache() {
 		return this.cleanCache;
 	}
 
-	void setCleanCache(Boolean cleanCache) {
+	void setCleanCache(@Nullable Boolean cleanCache) {
 		this.cleanCache = cleanCache;
 	}
 
@@ -165,11 +168,11 @@ public class Image {
 	 * If images should be pulled from a remote repository during image build.
 	 * @return the pull policy
 	 */
-	public PullPolicy getPullPolicy() {
+	public @Nullable PullPolicy getPullPolicy() {
 		return this.pullPolicy;
 	}
 
-	void setPullPolicy(PullPolicy pullPolicy) {
+	void setPullPolicy(@Nullable PullPolicy pullPolicy) {
 		this.pullPolicy = pullPolicy;
 	}
 
@@ -177,11 +180,11 @@ public class Image {
 	 * If the built image should be pushed to a registry.
 	 * @return {@code true} if the image should be published
 	 */
-	public Boolean getPublish() {
+	public @Nullable Boolean getPublish() {
 		return this.publish;
 	}
 
-	void setPublish(Boolean publish) {
+	void setPublish(@Nullable Boolean publish) {
 		this.publish = publish;
 	}
 
@@ -189,11 +192,11 @@ public class Image {
 	 * Returns the network the build container will connect to.
 	 * @return the network
 	 */
-	public String getNetwork() {
+	public @Nullable String getNetwork() {
 		return this.network;
 	}
 
-	public void setNetwork(String network) {
+	public void setNetwork(@Nullable String network) {
 		this.network = network;
 	}
 
@@ -201,11 +204,11 @@ public class Image {
 	 * Returns the created date for the image.
 	 * @return the created date
 	 */
-	public String getCreatedDate() {
+	public @Nullable String getCreatedDate() {
 		return this.createdDate;
 	}
 
-	public void setCreatedDate(String createdDate) {
+	public void setCreatedDate(@Nullable String createdDate) {
 		this.createdDate = createdDate;
 	}
 
@@ -213,11 +216,11 @@ public class Image {
 	 * Returns the application content directory for the image.
 	 * @return the application directory
 	 */
-	public String getApplicationDirectory() {
+	public @Nullable String getApplicationDirectory() {
 		return this.applicationDirectory;
 	}
 
-	public void setApplicationDirectory(String applicationDirectory) {
+	public void setApplicationDirectory(@Nullable String applicationDirectory) {
 		this.applicationDirectory = applicationDirectory;
 	}
 
@@ -227,11 +230,11 @@ public class Image {
 	 * operating system and architecture.
 	 * @return the image platform
 	 */
-	public String getImagePlatform() {
+	public @Nullable String getImagePlatform() {
 		return this.imagePlatform;
 	}
 
-	public void setImagePlatform(String imagePlatform) {
+	public void setImagePlatform(@Nullable String imagePlatform) {
 		this.imagePlatform = imagePlatform;
 	}
 
@@ -281,13 +284,19 @@ public class Image {
 			request = request.withTags(this.tags.stream().map(ImageReference::of).toList());
 		}
 		if (this.buildWorkspace != null) {
-			request = request.withBuildWorkspace(this.buildWorkspace.asCache());
+			Cache cache = this.buildWorkspace.asCache();
+			Assert.state(cache != null, "'cache' must not be null");
+			request = request.withBuildWorkspace(cache);
 		}
 		if (this.buildCache != null) {
-			request = request.withBuildCache(this.buildCache.asCache());
+			Cache cache = this.buildCache.asCache();
+			Assert.state(cache != null, "'cache' must not be null");
+			request = request.withBuildCache(cache);
 		}
 		if (this.launchCache != null) {
-			request = request.withLaunchCache(this.launchCache.asCache());
+			Cache cache = this.launchCache.asCache();
+			Assert.state(cache != null, "'cache' must not be null");
+			request = request.withLaunchCache(cache);
 		}
 		if (StringUtils.hasText(this.createdDate)) {
 			request = request.withCreatedDate(this.createdDate);

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/JavaCompilerPluginConfiguration.java

@@ -21,6 +21,9 @@ import java.util.Arrays;
 import org.apache.maven.model.Plugin;
 import org.apache.maven.project.MavenProject;
 import org.codehaus.plexus.util.xml.Xpp3Dom;
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.lang.Contract;
 
 /**
  * Provides access to the Maven Java Compiler plugin configuration.
@@ -35,7 +38,7 @@ class JavaCompilerPluginConfiguration {
 		this.project = project;
 	}
 
-	String getSourceMajorVersion() {
+	@Nullable String getSourceMajorVersion() {
 		String version = getConfigurationValue("source");
 
 		if (version == null) {
@@ -45,7 +48,7 @@ class JavaCompilerPluginConfiguration {
 		return majorVersionFor(version);
 	}
 
-	String getTargetMajorVersion() {
+	@Nullable String getTargetMajorVersion() {
 		String version = getConfigurationValue("target");
 
 		if (version == null) {
@@ -55,7 +58,7 @@ class JavaCompilerPluginConfiguration {
 		return majorVersionFor(version);
 	}
 
-	String getReleaseVersion() {
+	@Nullable String getReleaseVersion() {
 		String version = getConfigurationValue("release");
 
 		if (version == null) {
@@ -65,7 +68,7 @@ class JavaCompilerPluginConfiguration {
 		return majorVersionFor(version);
 	}
 
-	private String getConfigurationValue(String propertyName) {
+	private @Nullable String getConfigurationValue(String propertyName) {
 		Plugin plugin = this.project.getPlugin("org.apache.maven.plugins:maven-compiler-plugin");
 		if (plugin != null) {
 			Object pluginConfiguration = plugin.getConfiguration();
@@ -76,14 +79,14 @@ class JavaCompilerPluginConfiguration {
 		return null;
 	}
 
-	private String getPropertyValue(String propertyName) {
+	private @Nullable String getPropertyValue(String propertyName) {
 		if (this.project.getProperties().containsKey(propertyName)) {
 			return this.project.getProperties().get(propertyName).toString();
 		}
 		return null;
 	}
 
-	private String getNodeValue(Xpp3Dom dom, String... childNames) {
+	private @Nullable String getNodeValue(Xpp3Dom dom, String... childNames) {
 		Xpp3Dom childNode = dom.getChild(childNames[0]);
 
 		if (childNode == null) {
@@ -97,7 +100,8 @@ class JavaCompilerPluginConfiguration {
 		return childNode.getValue();
 	}
 
-	private String majorVersionFor(String version) {
+	@Contract("!null -> !null")
+	private @Nullable String majorVersionFor(@Nullable String version) {
 		if (version != null && version.startsWith("1.")) {
 			return version.substring("1.".length());
 		}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/JavaProcessExecutor.java

@@ -26,6 +26,7 @@ import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.toolchain.Toolchain;
 import org.apache.maven.toolchain.ToolchainManager;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.loader.tools.JavaExecutable;
 import org.springframework.boot.loader.tools.RunProcess;
@@ -43,14 +44,14 @@ class JavaProcessExecutor {
 
 	private final ToolchainManager toolchainManager;
 
-	private final Consumer<RunProcess> runProcessCustomizer;
+	private final @Nullable Consumer<RunProcess> runProcessCustomizer;
 
 	JavaProcessExecutor(MavenSession mavenSession, ToolchainManager toolchainManager) {
 		this(mavenSession, toolchainManager, null);
 	}
 
 	private JavaProcessExecutor(MavenSession mavenSession, ToolchainManager toolchainManager,
-			Consumer<RunProcess> runProcessCustomizer) {
+			@Nullable Consumer<RunProcess> runProcessCustomizer) {
 		this.mavenSession = mavenSession;
 		this.toolchainManager = toolchainManager;
 		this.runProcessCustomizer = runProcessCustomizer;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/Layers.java

@@ -18,6 +18,8 @@ package org.springframework.boot.maven;
 
 import java.io.File;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Layer configuration options.
  *
@@ -28,7 +30,7 @@ public class Layers {
 
 	private boolean enabled = true;
 
-	private File configuration;
+	private @Nullable File configuration;
 
 	/**
 	 * Whether a {@code layers.idx} file should be added to the jar.
@@ -44,11 +46,11 @@ public class Layers {
 	 * {@code snapshot-dependencies} and {@code dependencies}.
 	 * @return the layers configuration file
 	 */
-	public File getConfiguration() {
+	public @Nullable File getConfiguration() {
 		return this.configuration;
 	}
 
-	public void setConfiguration(File configuration) {
+	public void setConfiguration(@Nullable File configuration) {
 		this.configuration = configuration;
 	}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/MavenBuildOutputTimestamp.java

@@ -22,6 +22,8 @@ import java.time.OffsetDateTime;
 import java.time.ZoneOffset;
 import java.time.format.DateTimeParseException;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.StringUtils;
 
 /**
@@ -42,13 +44,13 @@ class MavenBuildOutputTimestamp {
 
 	private static final Instant DATE_MAX = Instant.parse("2099-12-31T23:59:59Z");
 
-	private final String timestamp;
+	private final @Nullable String timestamp;
 
 	/**
 	 * Creates a new {@link MavenBuildOutputTimestamp}.
 	 * @param timestamp timestamp or {@code null}
 	 */
-	MavenBuildOutputTimestamp(String timestamp) {
+	MavenBuildOutputTimestamp(@Nullable String timestamp) {
 		this.timestamp = timestamp;
 	}
 
@@ -59,7 +61,7 @@ class MavenBuildOutputTimestamp {
 	 * integer, or it's not within the valid range 1980-01-01T00:00:02Z to
 	 * 2099-12-31T23:59:59Z
 	 */
-	FileTime toFileTime() {
+	@Nullable FileTime toFileTime() {
 		Instant instant = toInstant();
 		if (instant == null) {
 			return null;
@@ -74,7 +76,7 @@ class MavenBuildOutputTimestamp {
 	 * integer, or it's not within the valid range 1980-01-01T00:00:02Z to
 	 * 2099-12-31T23:59:59Z
 	 */
-	Instant toInstant() {
+	@Nullable Instant toInstant() {
 		if (!StringUtils.hasLength(this.timestamp)) {
 			return null;
 		}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/ProcessAotMojo.java

@@ -28,6 +28,7 @@ import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
 import org.apache.maven.toolchain.ToolchainManager;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.ObjectUtils;
 
@@ -50,24 +51,28 @@ public class ProcessAotMojo extends AbstractAotMojo {
 	 * the archive.
 	 */
 	@Parameter(defaultValue = "${project.build.outputDirectory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File classesDirectory;
 
 	/**
 	 * Directory containing the generated sources.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/main/sources", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedSources;
 
 	/**
 	 * Directory containing the generated resources.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/main/resources", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedResources;
 
 	/**
 	 * Directory containing the generated classes.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/main/classes", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedClasses;
 
 	/**
@@ -75,18 +80,20 @@ public class ProcessAotMojo extends AbstractAotMojo {
 	 * the first compiled class found that contains a 'main' method will be used.
 	 */
 	@Parameter(property = "spring-boot.aot.main-class")
-	private String mainClass;
+	private @Nullable String mainClass;
 
 	/**
 	 * Application arguments that should be taken into account for AOT processing.
 	 */
 	@Parameter
+	@SuppressWarnings("NullAway") // maven-maven-plugin can't handle annotated arrays
 	private String[] arguments;
 
 	/**
 	 * Spring profiles to take into account for AOT processing.
 	 */
 	@Parameter
+	@SuppressWarnings("NullAway") // maven-maven-plugin can't handle annotated arrays
 	private String[] profiles;
 
 	@Inject

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/ProcessTestAotMojo.java

@@ -71,6 +71,7 @@ public class ProcessTestAotMojo extends AbstractAotMojo {
 	 * the archive.
 	 */
 	@Parameter(defaultValue = "${project.build.testOutputDirectory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File testClassesDirectory;
 
 	/**
@@ -78,30 +79,35 @@ public class ProcessTestAotMojo extends AbstractAotMojo {
 	 * tests.
 	 */
 	@Parameter(defaultValue = "${project.build.outputDirectory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File classesDirectory;
 
 	/**
 	 * Directory containing the generated sources.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/test/sources", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedSources;
 
 	/**
 	 * Directory containing the generated test resources.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/test/resources", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedResources;
 
 	/**
 	 * Directory containing the generated test classes.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/test/classes", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedTestClasses;
 
 	/**
 	 * Directory containing the generated test classes.
 	 */
 	@Parameter(defaultValue = "${project.build.directory}/spring-aot/main/classes", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File generatedClasses;
 
 	private final RepositorySystem repositorySystem;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/PropertiesMergingResourceTransformer.java

@@ -25,6 +25,7 @@ import java.util.jar.JarOutputStream;
 
 import org.apache.maven.plugins.shade.relocation.Relocator;
 import org.apache.maven.plugins.shade.resource.ReproducibleResourceTransformer;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Extension for the <a href="https://maven.apache.org/plugins/maven-shade-plugin/">Maven
@@ -38,7 +39,7 @@ import org.apache.maven.plugins.shade.resource.ReproducibleResourceTransformer;
 public class PropertiesMergingResourceTransformer implements ReproducibleResourceTransformer {
 
 	// Set this in pom configuration with <resource>...</resource>
-	private String resource;
+	private @Nullable String resource;
 
 	private final Properties data = new Properties();
 
@@ -95,11 +96,11 @@ public class PropertiesMergingResourceTransformer implements ReproducibleResourc
 		this.data.clear();
 	}
 
-	public String getResource() {
+	public @Nullable String getResource() {
 		return this.resource;
 	}
 
-	public void setResource(String resource) {
+	public void setResource(@Nullable String resource) {
 		this.resource = resource;
 	}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RepackageMojo.java

@@ -34,6 +34,7 @@ import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
 import org.apache.maven.project.MavenProjectHelper;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.loader.tools.DefaultLaunchScript;
 import org.springframework.boot.loader.tools.LaunchScript;
@@ -41,6 +42,7 @@ import org.springframework.boot.loader.tools.LayoutFactory;
 import org.springframework.boot.loader.tools.Libraries;
 import org.springframework.boot.loader.tools.LoaderImplementation;
 import org.springframework.boot.loader.tools.Repackager;
+import org.springframework.lang.Contract;
 import org.springframework.util.StringUtils;
 
 /**
@@ -67,13 +69,15 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter(defaultValue = "${project.build.directory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File outputDirectory;
 
 	/**
 	 * Name of the generated archive.
 	 * @since 1.0.0
 	 */
-	@Parameter(defaultValue = "${project.build.finalName}", readonly = true)
+	@Parameter(defaultValue = "${project.build.finalName}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	private String finalName;
 
 	/**
@@ -96,7 +100,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter
-	private String classifier;
+	private @Nullable String classifier;
 
 	/**
 	 * Attach the repackaged archive to be installed into your local Maven repository or
@@ -117,7 +121,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 1.1.0
 	 */
 	@Parameter
-	private List<Dependency> requiresUnpack;
+	private @Nullable List<Dependency> requiresUnpack;
 
 	/**
 	 * Make a fully executable jar for *nix machines by prepending a launch script to the
@@ -139,14 +143,14 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 1.3.0
 	 */
 	@Parameter
-	private File embeddedLaunchScript;
+	private @Nullable File embeddedLaunchScript;
 
 	/**
 	 * Properties that should be expanded in the embedded launch script.
 	 * @since 1.3.0
 	 */
 	@Parameter
-	private Properties embeddedLaunchScriptProperties;
+	private @Nullable Properties embeddedLaunchScriptProperties;
 
 	/**
 	 * Timestamp for reproducible output archive entries, either formatted as ISO 8601
@@ -155,7 +159,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 2.3.0
 	 */
 	@Parameter(defaultValue = "${project.build.outputTimestamp}")
-	private String outputTimestamp;
+	private @Nullable String outputTimestamp;
 
 	/**
 	 * The type of archive (which corresponds to how the dependencies are laid out inside
@@ -164,14 +168,14 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 1.0.0
 	 */
 	@Parameter(property = "spring-boot.repackage.layout")
-	private LayoutType layout;
+	private @Nullable LayoutType layout;
 
 	/**
 	 * The loader implementation that should be used.
 	 * @since 3.2.0
 	 */
 	@Parameter
-	private LoaderImplementation loaderImplementation;
+	private @Nullable LoaderImplementation loaderImplementation;
 
 	/**
 	 * The layout factory that will be used to create the executable archive if no
@@ -180,7 +184,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * @since 1.5.0
 	 */
 	@Parameter
-	private LayoutFactory layoutFactory;
+	private @Nullable LayoutFactory layoutFactory;
 
 	@Inject
 	public RepackageMojo(MavenProjectHelper projectHelper) {
@@ -193,12 +197,12 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * is not provided
 	 */
 	@Override
-	protected LayoutType getLayout() {
+	protected @Nullable LayoutType getLayout() {
 		return this.layout;
 	}
 
 	@Override
-	protected LoaderImplementation getLoaderImplementation() {
+	protected @Nullable LoaderImplementation getLoaderImplementation() {
 		return this.loaderImplementation;
 	}
 
@@ -209,7 +213,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 	 * parameter is not provided
 	 */
 	@Override
-	protected LayoutFactory getLayoutFactory() {
+	protected @Nullable LayoutFactory getLayoutFactory() {
 		return this.layoutFactory;
 	}
 
@@ -245,7 +249,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 		updateArtifact(source, target, repackager.getBackupFile());
 	}
 
-	private FileTime parseOutputTimestamp() throws MojoExecutionException {
+	private @Nullable FileTime parseOutputTimestamp() throws MojoExecutionException {
 		try {
 			return new MavenBuildOutputTimestamp(this.outputTimestamp).toFileTime();
 		}
@@ -258,7 +262,7 @@ public class RepackageMojo extends AbstractPackagerMojo {
 		return getConfiguredPackager(() -> new Repackager(source));
 	}
 
-	private LaunchScript getLaunchScript() throws IOException {
+	private @Nullable LaunchScript getLaunchScript() throws IOException {
 		if (this.executable || this.embeddedLaunchScript != null) {
 			return new DefaultLaunchScript(this.embeddedLaunchScript, buildLaunchScriptProperties());
 		}
@@ -277,7 +281,8 @@ public class RepackageMojo extends AbstractPackagerMojo {
 		return properties;
 	}
 
-	private String removeLineBreaks(String description) {
+	@Contract("!null -> !null")
+	private @Nullable String removeLineBreaks(@Nullable String description) {
 		return (description != null) ? WHITE_SPACE_PATTERN.matcher(description).replaceAll(" ") : null;
 	}
 

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RunArguments.java

@@ -22,6 +22,7 @@ import java.util.LinkedList;
 import java.util.Objects;
 
 import org.codehaus.plexus.util.cli.CommandLineUtils;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Parse and expose arguments specified in a single string.
@@ -34,7 +35,7 @@ class RunArguments {
 
 	private final Deque<String> args = new LinkedList<>();
 
-	RunArguments(String arguments) {
+	RunArguments(@Nullable String arguments) {
 		this(parseArgs(arguments));
 	}
 
@@ -52,7 +53,7 @@ class RunArguments {
 		return this.args.toArray(new String[0]);
 	}
 
-	private static String[] parseArgs(String arguments) {
+	private static String[] parseArgs(@Nullable String arguments) {
 		if (arguments == null || arguments.trim().isEmpty()) {
 			return NO_ARGS;
 		}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RunMojo.java

@@ -59,7 +59,7 @@ public class RunMojo extends AbstractRunMojo {
 	 * @since 1.3.0
 	 */
 	@Parameter(property = "spring-boot.run.useTestClasspath", defaultValue = "false")
-	private Boolean useTestClasspath;
+	private boolean useTestClasspath;
 
 	@Inject
 	public RunMojo(ToolchainManager toolchainManager) {

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/StartMojo.java

@@ -36,6 +36,7 @@ import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
 import org.apache.maven.toolchain.ToolchainManager;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.loader.tools.RunProcess;
 
@@ -62,6 +63,7 @@ public class StartMojo extends AbstractRunMojo {
 	 * spring application.
 	 */
 	@Parameter(defaultValue = SpringApplicationAdminClient.DEFAULT_OBJECT_NAME)
+	@SuppressWarnings("NullAway.Init")
 	private String jmxName;
 
 	/**
@@ -91,7 +93,7 @@ public class StartMojo extends AbstractRunMojo {
 	 * Flag to include the test classpath when running.
 	 */
 	@Parameter(property = "spring-boot.run.useTestClasspath", defaultValue = "false")
-	private Boolean useTestClasspath;
+	private boolean useTestClasspath;
 
 	@Inject
 	public StartMojo(ToolchainManager toolchainManager) {
@@ -154,6 +156,7 @@ public class StartMojo extends AbstractRunMojo {
 		}
 	}
 
+	@SuppressWarnings("NullAway") // Lambda isn't detected with the correct nullability
 	private void doWaitForSpringApplication(MBeanServerConnection connection)
 			throws MojoExecutionException, MojoFailureException {
 		final SpringApplicationAdminClient client = new SpringApplicationAdminClient(connection, this.jmxName);
@@ -178,7 +181,7 @@ public class StartMojo extends AbstractRunMojo {
 	 * @return the result
 	 * @throws Exception in case of execution errors
 	 */
-	public <T> T execute(long wait, int maxAttempts, Callable<T> callback) throws Exception {
+	public <T> T execute(long wait, int maxAttempts, Callable<@Nullable T> callback) throws Exception {
 		getLog().debug("Waiting for spring application to start...");
 		for (int i = 0; i < maxAttempts; i++) {
 			T result = callback.call();
@@ -206,7 +209,7 @@ public class StartMojo extends AbstractRunMojo {
 		return this.useTestClasspath;
 	}
 
-	private class CreateJmxConnector implements Callable<JMXConnector> {
+	private class CreateJmxConnector implements Callable<@Nullable JMXConnector> {
 
 		private final int port;
 
@@ -215,7 +218,7 @@ public class StartMojo extends AbstractRunMojo {
 		}
 
 		@Override
-		public JMXConnector call() throws Exception {
+		public @Nullable JMXConnector call() throws Exception {
 			try {
 				return SpringApplicationAdminClient.connect(this.port);
 			}

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/StopMojo.java

@@ -45,6 +45,7 @@ public class StopMojo extends AbstractMojo {
 	 * @since 1.4.1
 	 */
 	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	private MavenProject project;
 
 	/**
@@ -52,6 +53,7 @@ public class StopMojo extends AbstractMojo {
 	 * application.
 	 */
 	@Parameter(defaultValue = SpringApplicationAdminClient.DEFAULT_OBJECT_NAME)
+	@SuppressWarnings("NullAway.Init")
 	private String jmxName;
 
 	/**

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/TestRunMojo.java

@@ -62,6 +62,7 @@ public class TestRunMojo extends AbstractRunMojo {
 	 * the application.
 	 */
 	@Parameter(defaultValue = "${project.build.testOutputDirectory}", required = true)
+	@SuppressWarnings("NullAway.Init")
 	private File testClassesDirectory;
 
 	@Inject

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/VersionExtractor.java

@@ -24,6 +24,8 @@ import java.net.URLConnection;
 import java.util.jar.Attributes;
 import java.util.jar.JarFile;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Extracts version information for a Class.
  *
@@ -40,7 +42,7 @@ final class VersionExtractor {
 	 * @param cls the Class to retrieve the version for
 	 * @return the version, or {@code null} if a version can not be extracted
 	 */
-	static String forClass(Class<?> cls) {
+	static @Nullable String forClass(Class<?> cls) {
 		String implementationVersion = cls.getPackage().getImplementationVersion();
 		if (implementationVersion != null) {
 			return implementationVersion;

build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Maven plugin for Spring Boot.
  */
+@NullMarked
 package org.springframework.boot.maven;
+
+import org.jspecify.annotations.NullMarked;