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

See gh-46587

Author: mhalbritter

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

@@ -44,6 +44,7 @@
 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.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 @@ private FilterArtifacts getFilters(ArtifactsFilter... additionalFilters) {
 		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.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;
 
@@ -67,13 +68,15 @@ public abstract class AbstractPackagerMojo extends AbstractDependencyFilterMojo
 	 * @since 1.0.0
 	 */
 	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	@SuppressWarnings("NullAway.Init")
 	protected MavenProject project;
 
 	/**
 	 * The Maven session.
 	 * @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 @@ protected AbstractPackagerMojo(MavenProjectHelper projectHelper) {
 	 * @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 @@ protected LayoutType getLayout() {
 	 * @return the loader implementation or {@code null}
 	 * @since 3.2.0
 	 */
-	protected LoaderImplementation getLoaderImplementation() {
+	protected @Nullable LoaderImplementation getLoaderImplementation() {
 		return null;
 	}
 
@@ -153,7 +156,7 @@ protected LoaderImplementation getLoaderImplementation() {
 	 * 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 @@ private Document getDocumentIfAvailable(File xmlFile) throws Exception {
 	 * @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 @@ private ArtifactsFilter[] getAdditionalFilters() {
 	 * @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 @@ private Artifact getArtifact(String classifier) {
 		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.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
@@ -121,15 +125,15 @@ 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.
 	 *
 	 * @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
@@ -138,14 +142,15 @@ 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.
 	 *
 	 * @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 @@ private void addAgents(List<String> args) {
 	}
 
 	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 @@ private void logArguments(String name, String[] args) {
 	 */
 	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.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 ArtifactsLibraries(Set<Artifact> artifacts, Collection<MavenProject> loca
 	 * @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;