Migrate to JSpecify annotations for nullability constraints.

Closes #2450

Author: mp911de

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/AggregateReference.java

@@ -18,7 +18,7 @@
 import java.net.URI;
 import java.util.function.Function;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.web.util.UriComponents;
 
 /**

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/AssociationAggregateReference.java

@@ -20,7 +20,7 @@
 import org.jmolecules.ddd.types.AggregateRoot;
 import org.jmolecules.ddd.types.Association;
 import org.jmolecules.ddd.types.Identifier;
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.web.util.UriComponents;
 
 /**

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/Path.java

@@ -17,7 +17,7 @@
 
 import java.util.regex.Pattern;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.util.StringUtils;
 
 /**

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/RepositoryConstraintViolationException.java

@@ -1,16 +1,18 @@
 package org.springframework.data.rest.core;
 
+import java.io.Serial;
+
 import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.validation.Errors;
 
 /**
  * Exception that is thrown when a Spring {@link org.springframework.validation.Validator} throws an error.
- * 
+ *
  * @author Jon Brisbin
  */
 public class RepositoryConstraintViolationException extends DataIntegrityViolationException {
 
-	private static final long serialVersionUID = -4789377071564956366L;
+	private static final @Serial long serialVersionUID = -4789377071564956366L;
 
 	private final Errors errors;
 

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/ResolvingAggregateReference.java

@@ -18,7 +18,7 @@
 import java.net.URI;
 import java.util.function.Function;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/UriToEntityConverter.java

@@ -20,17 +20,18 @@
 import java.util.Set;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.convert.ConversionFailedException;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.GenericConverter;
+import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.context.PersistentEntities;
 import org.springframework.data.repository.support.Repositories;
 import org.springframework.data.repository.support.RepositoryInvokerFactory;
 import org.springframework.data.util.ClassUtils;
 import org.springframework.data.util.TypeInformation;
-import org.springframework.lang.NonNull;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -41,7 +42,8 @@
  */
 public class UriToEntityConverter implements GenericConverter {
 
-	private static final Class<?> ASSOCIATION_TYPE = ClassUtils.loadIfPresent("org.jmolecules.ddd.types.Association",
+	private static final @Nullable Class<?> ASSOCIATION_TYPE = ClassUtils
+			.loadIfPresent("org.jmolecules.ddd.types.Association",
 			UriToEntityConverter.class.getClassLoader());
 
 	private final PersistentEntities entities;
@@ -74,7 +76,7 @@ public UriToEntityConverter(PersistentEntities entities, RepositoryInvokerFactor
 			var rawType = domainType.getType();
 			var entity = entities.getPersistentEntity(rawType);
 
-			entity.filter(it -> it.hasIdProperty()).ifPresent(it -> {
+			entity.filter(PersistentEntity::hasIdProperty).ifPresent(it -> {
 				convertiblePairs.add(new ConvertiblePair(URI.class, domainType.getType()));
 				registerIdentifierType(it.getRequiredIdProperty().getType());
 			});
@@ -95,7 +97,6 @@ private void registerIdentifierType(Class<?> type) {
 		identifierTypes.add(type);
 	}
 
-	@NonNull
 	@Override
 	public Set<ConvertiblePair> getConvertibleTypes() {
 		return convertiblePairs;

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/ValidationErrors.java

@@ -15,11 +15,14 @@
  */
 package org.springframework.data.rest.core;
 
+import java.io.Serial;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Optional;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.BeansException;
 import org.springframework.beans.ConfigurablePropertyAccessor;
 import org.springframework.beans.DirectFieldAccessor;
@@ -29,7 +32,6 @@
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.context.PersistentEntities;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.validation.AbstractPropertyBindingResult;
 
@@ -44,7 +46,7 @@
  */
 public class ValidationErrors extends AbstractPropertyBindingResult {
 
-	private static final long serialVersionUID = 8141826537389141361L;
+	private static final @Serial long serialVersionUID = 8141826537389141361L;
 
 	private final Object source;
 	private final PersistentEntities entities;
@@ -72,6 +74,7 @@ public ConfigurablePropertyAccessor getPropertyAccessor() {
 		return new DirectFieldAccessor(getTarget()) {
 
 			@Override
+			@Nullable
 			public Object getPropertyValue(String propertyName) throws BeansException {
 
 				Collection<String> segments = Arrays.asList(propertyName.split("\\."));
@@ -82,7 +85,7 @@ public Object getPropertyValue(String propertyName) throws BeansException {
 
 					value = lookupValueOn(value, iterator.next());
 
-				} while (iterator.hasNext());
+				} while (value != null && iterator.hasNext());
 
 				return value;
 			}

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/annotation/package-info.java

@@ -0,0 +1,2 @@
+@org.jspecify.annotations.NullMarked
+package org.springframework.data.rest.core.annotation;

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/config/EntityLookupConfiguration.java

@@ -20,6 +20,8 @@
 import java.util.Objects;
 import java.util.Optional;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.repository.Repository;
 import org.springframework.data.repository.core.RepositoryInformation;
@@ -29,7 +31,6 @@
 import org.springframework.data.rest.core.support.EntityLookup;
 import org.springframework.data.util.MethodInvocationRecorder;
 import org.springframework.data.util.StreamUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -41,7 +42,7 @@
  */
 class EntityLookupConfiguration implements EntityLookupRegistrar {
 
-	private final List<LookupInformation<Object, Object, Repository<? extends Object, ?>>> lookupInformation = new ArrayList<>();
+	private final List<LookupInformation<Object, Object, Repository<?, ?>>> lookupInformation = new ArrayList<>();
 	private final List<Class<?>> lookupTypes = new ArrayList<>();
 
 	@Override
@@ -84,7 +85,7 @@ private class MappingBuilder<T, ID, R extends Repository<T, ?>>
 			implements LookupRegistrar<T, ID, R>, IdMappingRegistrar<T, R> {
 
 		private final Class<R> repositoryType;
-		private Converter<T, ID> idMapping;
+		private @Nullable Converter<T, ID> idMapping;
 
 		/**
 		 * Creates a new {@link MappingBuilder} for the given repository type.
@@ -114,8 +115,10 @@ private MappingBuilder(Class<R> repositoryType, Converter<T, ID> mapping) {
 		@SuppressWarnings("unchecked")
 		public EntityLookupRegistrar withLookup(Lookup<R, ID> lookup) {
 
+			Assert.notNull(idMapping, "IdMapping must not be null");
+
 			EntityLookupConfiguration.this.lookupInformation
-					.add((LookupInformation<Object, Object, Repository<? extends Object, ?>>) new LookupInformation<T, ID, R>(
+					.add((LookupInformation<Object, Object, Repository<?, ?>>) new LookupInformation<T, ID, R>(
 							repositoryType, idMapping, lookup));
 
 			return EntityLookupConfiguration.this;
@@ -186,7 +189,7 @@ public RepositoriesEntityLookup(Repositories repositories,
 
 		@Override
 		public Object getResourceIdentifier(T entity) {
-			return lookupInfo.getIdentifierMapping().convert(entity);
+			return Objects.requireNonNull(lookupInfo.getIdentifierMapping().convert(entity));
 		}
 
 		@Override
@@ -239,7 +242,7 @@ public Lookup<R, ID> getLookup() {
 		}
 
 		@Override
-		public boolean equals(@Nullable final java.lang.Object o) {
+		public boolean equals(@Nullable Object o) {
 
 			if (o == this) {
 				return true;

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/config/MetadataConfiguration.java

@@ -20,6 +20,8 @@
 import java.util.Map.Entry;
 import java.util.regex.Pattern;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -29,8 +31,8 @@
  */
 public class MetadataConfiguration {
 
-	private final Map<Class<?>, JsonSchemaFormat> schemaFormats = new HashMap<Class<?>, JsonSchemaFormat>();
-	private final Map<Class<?>, Pattern> patterns = new HashMap<Class<?>, Pattern>();
+	private final Map<Class<?>, JsonSchemaFormat> schemaFormats = new HashMap<>();
+	private final Map<Class<?>, Pattern> patterns = new HashMap<>();
 	private boolean omitUnresolvableDescriptionKeys = true;
 	private boolean alpsEnabled = true;
 
@@ -88,7 +90,7 @@ public void registerJsonSchemaFormat(JsonSchemaFormat format, Class<?>... types)
 	 * @param type must not be {@literal null}.
 	 * @return
 	 */
-	public JsonSchemaFormat getSchemaFormatFor(Class<?> type) {
+	public @Nullable JsonSchemaFormat getSchemaFormatFor(Class<?> type) {
 		return schemaFormats.get(type);
 	}
 
@@ -112,7 +114,7 @@ public void registerFormattingPatternFor(String pattern, Class<?> type) {
 	 * @param type must not be {@literal null}.
 	 * @return
 	 */
-	public Pattern getPatternFor(Class<?> type) {
+	public @Nullable Pattern getPatternFor(Class<?> type) {
 
 		Assert.notNull(type, "Type must not be null");