Add missing Nullable annotations

Author: jjohannes

src/main/java/org/gradlex/javamodule/moduleinfo/ModuleInfo.java

@@ -17,6 +17,7 @@
 package org.gradlex.javamodule.moduleinfo;
 
 import org.gradle.api.model.ObjectFactory;
+import org.jspecify.annotations.Nullable;
 
 import java.util.Arrays;
 import java.util.LinkedHashMap;
@@ -30,6 +31,7 @@
 @SuppressWarnings("unused")
 public class ModuleInfo extends ModuleSpec {
 
+    @Nullable
     private final String moduleVersion;
 
     boolean openModule = true;
@@ -47,7 +49,7 @@ public class ModuleInfo extends ModuleSpec {
     boolean patchRealModule;
     boolean preserveExisting;
 
-    ModuleInfo(String identifier, String moduleName, String moduleVersion, ObjectFactory objectFactory) {
+    ModuleInfo(String identifier, String moduleName, @Nullable String moduleVersion, ObjectFactory objectFactory) {
         super(identifier, moduleName);
         this.moduleVersion = moduleVersion;
     }
@@ -124,6 +126,7 @@ public void ignoreServiceProvider(String provider, String... implementations) {
     /**
      * @return configured version of the Module
      */
+    @Nullable
     public String getModuleVersion() {
         return moduleVersion;
     }

src/main/java/org/gradlex/javamodule/moduleinfo/ModuleSpec.java

@@ -18,6 +18,7 @@
 
 import org.gradle.api.artifacts.MinimalExternalModuleDependency;
 import org.gradle.api.provider.Provider;
+import org.jspecify.annotations.Nullable;
 
 import java.io.Serializable;
 import java.util.ArrayList;
@@ -33,6 +34,7 @@
 public abstract class ModuleSpec implements Serializable {
 
     private final String identifier;
+    @Nullable
     private final String classifier; // optional
     private final String moduleName;
     private final List<String> removedPackages = new ArrayList<>();
@@ -63,6 +65,7 @@ public String getIdentifier() {
     /**
      * @return classifier, as an addition to group:name coordinates, if defined
      */
+    @Nullable
     public String getClassifier() {
         return classifier;
     }

src/main/java/org/gradlex/javamodule/moduleinfo/PublishedMetadata.java

@@ -33,6 +33,7 @@
 import org.gradle.api.tasks.SourceSet;
 import org.gradle.api.tasks.SourceSetContainer;
 import org.gradle.util.GradleVersion;
+import org.jspecify.annotations.Nullable;
 
 import java.io.Serializable;
 import java.util.ArrayList;
@@ -54,6 +55,7 @@ public class PublishedMetadata implements Serializable {
     private final List<String> requires = new ArrayList<>();
     private final List<String> requiresTransitive = new ArrayList<>();
     private final List<String> requiresStaticTransitive = new ArrayList<>();
+    @Nullable
     private String errorMessage = null;
 
     PublishedMetadata(String gav, Project project, ExtraJavaModuleInfoPluginExtension extension) {
@@ -95,7 +97,7 @@ private List<String> componentVariant(Provider<String> versionsProvidingConfigur
         return firstAndOnlyComponentDependencies(singleComponentVariantResolver);
     }
 
-    private Configuration maybeCreateDefaultVersionSourcConfiguration(ConfigurationContainer configurations, ObjectFactory objects, SourceSetContainer sourceSets) {
+    private Configuration maybeCreateDefaultVersionSourcConfiguration(ConfigurationContainer configurations, ObjectFactory objects, @Nullable SourceSetContainer sourceSets) {
         String name = DEFAULT_VERSION_SOURCE_CONFIGURATION;
         Configuration existing = configurations.findByName(name);
         if (existing != null) {
@@ -174,6 +176,7 @@ public List<String> getRequiresStaticTransitive() {
         return requiresStaticTransitive;
     }
 
+    @Nullable
     public String getErrorMessage() {
         return errorMessage;
     }