Improve null-safety of loader/spring-boot-loader-tools

See gh-47263

loader/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/DefaultLaunchScript.java

@@ -58,7 +58,7 @@ public class DefaultLaunchScript implements LaunchScript {
 	 * @param properties an optional set of script properties used for variable expansion
 	 * @throws IOException if the script cannot be loaded
 	 */
-	public DefaultLaunchScript(@Nullable File file, Map<?, ?> properties) throws IOException {
+	public DefaultLaunchScript(@Nullable File file, @Nullable Map<?, ?> properties) throws IOException {
 		String content = loadContent(file);
 		this.content = expandPlaceholders(content, properties);
 	}

loader/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/DefaultLibraryCoordinates.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.loader.tools;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Encapsulates information about the artifact coordinates of a library.
  *
@@ -23,11 +25,11 @@ package org.springframework.boot.loader.tools;
  */
 class DefaultLibraryCoordinates implements LibraryCoordinates {
 
-	private final String groupId;
+	private final @Nullable String groupId;
 
-	private final String artifactId;
+	private final @Nullable String artifactId;
 
-	private final String version;
+	private final @Nullable String version;
 
 	/**
 	 * Create a new instance from discrete elements.
@@ -35,7 +37,7 @@ class DefaultLibraryCoordinates implements LibraryCoordinates {
 	 * @param artifactId the artifact ID
 	 * @param version the version
 	 */
-	DefaultLibraryCoordinates(String groupId, String artifactId, String version) {
+	DefaultLibraryCoordinates(@Nullable String groupId, @Nullable String artifactId, @Nullable String version) {
 		this.groupId = groupId;
 		this.artifactId = artifactId;
 		this.version = version;
@@ -46,7 +48,7 @@ class DefaultLibraryCoordinates implements LibraryCoordinates {
 	 * @return the group ID
 	 */
 	@Override
-	public String getGroupId() {
+	public @Nullable String getGroupId() {
 		return this.groupId;
 	}
 
@@ -55,7 +57,7 @@ class DefaultLibraryCoordinates implements LibraryCoordinates {
 	 * @return the artifact ID
 	 */
 	@Override
-	public String getArtifactId() {
+	public @Nullable String getArtifactId() {
 		return this.artifactId;
 	}
 
@@ -64,7 +66,7 @@ class DefaultLibraryCoordinates implements LibraryCoordinates {
 	 * @return the version
 	 */
 	@Override
-	public String getVersion() {
+	public @Nullable String getVersion() {
 		return this.version;
 	}
 

loader/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/LibraryCoordinates.java

@@ -31,19 +31,19 @@ public interface LibraryCoordinates {
 	 * Return the group ID of the coordinates.
 	 * @return the group ID
 	 */
-	String getGroupId();
+	@Nullable String getGroupId();
 
 	/**
 	 * Return the artifact ID of the coordinates.
 	 * @return the artifact ID
 	 */
-	String getArtifactId();
+	@Nullable String getArtifactId();
 
 	/**
 	 * Return the version of the coordinates.
 	 * @return the version
 	 */
-	String getVersion();
+	@Nullable String getVersion();
 
 	/**
 	 * Factory method to create {@link LibraryCoordinates} with the specified values.
@@ -52,7 +52,7 @@ public interface LibraryCoordinates {
 	 * @param version the version
 	 * @return a new {@link LibraryCoordinates} instance
 	 */
-	static LibraryCoordinates of(String groupId, String artifactId, String version) {
+	static LibraryCoordinates of(@Nullable String groupId, @Nullable String artifactId, @Nullable String version) {
 		return new DefaultLibraryCoordinates(groupId, artifactId, version);
 	}
 

loader/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/MainClassFinder.java

@@ -173,7 +173,7 @@ public abstract class MainClassFinder {
 	 * @return the main class or {@code null}
 	 * @throws IOException if the jar file cannot be read
 	 */
-	public static @Nullable String findMainClass(JarFile jarFile, String classesLocation) throws IOException {
+	public static @Nullable String findMainClass(JarFile jarFile, @Nullable String classesLocation) throws IOException {
 		return doWithMainClasses(jarFile, classesLocation, MainClass::getName);
 	}
 
@@ -184,7 +184,8 @@ public abstract class MainClassFinder {
 	 * @return the main class or {@code null}
 	 * @throws IOException if the jar file cannot be read
 	 */
-	public static @Nullable String findSingleMainClass(JarFile jarFile, String classesLocation) throws IOException {
+	public static @Nullable String findSingleMainClass(JarFile jarFile, @Nullable String classesLocation)
+			throws IOException {
 		return findSingleMainClass(jarFile, classesLocation, null);
 	}
 
@@ -199,7 +200,7 @@ public abstract class MainClassFinder {
 	 * @return the main class or {@code null}
 	 * @throws IOException if the jar file cannot be read
 	 */
-	public static @Nullable String findSingleMainClass(JarFile jarFile, String classesLocation,
+	public static @Nullable String findSingleMainClass(JarFile jarFile, @Nullable String classesLocation,
 			@Nullable String annotationName) throws IOException {
 		SingleMainClassCallback callback = new SingleMainClassCallback(annotationName);
 		MainClassFinder.doWithMainClasses(jarFile, classesLocation, callback);
@@ -215,8 +216,8 @@ public abstract class MainClassFinder {
 	 * @return the first callback result or {@code null}
 	 * @throws IOException in case of I/O errors
 	 */
-	static <T> @Nullable T doWithMainClasses(JarFile jarFile, String classesLocation, MainClassCallback<T> callback)
-			throws IOException {
+	static <T> @Nullable T doWithMainClasses(JarFile jarFile, @Nullable String classesLocation,
+			MainClassCallback<T> callback) throws IOException {
 		List<JarEntry> classEntries = getClassEntries(jarFile, classesLocation);
 		classEntries.sort(new ClassEntryComparator());
 		for (JarEntry entry : classEntries) {

loader/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/layer/IncludeExcludeContentSelector.java

@@ -42,8 +42,8 @@ public class IncludeExcludeContentSelector<T> implements ContentSelector<T> {
 
 	private final List<ContentFilter<T>> excludes;
 
-	public IncludeExcludeContentSelector(Layer layer, List<ContentFilter<T>> includes,
-			List<ContentFilter<T>> excludes) {
+	public IncludeExcludeContentSelector(Layer layer, @Nullable List<ContentFilter<T>> includes,
+			@Nullable List<ContentFilter<T>> excludes) {
 		this(layer, includes, excludes, Function.identity());
 	}