diff --git a/pom.xml b/pom.xml
index bb494b3..a006a44 100644
--- a/pom.xml
+++ b/pom.xml
@@ -95,6 +95,11 @@
 			<version>${cdi}</version>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.jspecify</groupId>
+			<artifactId>jspecify</artifactId>
+			<version>1.0.0</version>
+		</dependency>
 
 		<dependency>
 			<groupId>jakarta.annotation</groupId>
diff --git a/src/main/java/org/springframework/data/ldap/config/package-info.java b/src/main/java/org/springframework/data/ldap/config/package-info.java
index 413d7df..9e8fb95 100644
--- a/src/main/java/org/springframework/data/ldap/config/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/config/package-info.java
@@ -1,7 +1,5 @@
 /**
  * XML configuration support for Spring Data LDAP repositories.
  */
-@NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.config;
-
-import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/ldap/core/mapping/BasicLdapPersistentEntity.java b/src/main/java/org/springframework/data/ldap/core/mapping/BasicLdapPersistentEntity.java
index 8d581c8..1768f5b 100644
--- a/src/main/java/org/springframework/data/ldap/core/mapping/BasicLdapPersistentEntity.java
+++ b/src/main/java/org/springframework/data/ldap/core/mapping/BasicLdapPersistentEntity.java
@@ -35,4 +35,5 @@ public class BasicLdapPersistentEntity<T> extends BasicPersistentEntity<T, LdapP
 	public BasicLdapPersistentEntity(TypeInformation<T> information) {
 		super(information);
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/core/mapping/LdapMappingContext.java b/src/main/java/org/springframework/data/ldap/core/mapping/LdapMappingContext.java
index 3948e4a..88825ba 100644
--- a/src/main/java/org/springframework/data/ldap/core/mapping/LdapMappingContext.java
+++ b/src/main/java/org/springframework/data/ldap/core/mapping/LdapMappingContext.java
@@ -45,4 +45,5 @@ public class LdapMappingContext extends AbstractMappingContext<BasicLdapPersiste
 			SimpleTypeHolder simpleTypeHolder) {
 		return new LdapPersistentProperty(property, owner, simpleTypeHolder);
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/core/mapping/LdapPersistentProperty.java b/src/main/java/org/springframework/data/ldap/core/mapping/LdapPersistentProperty.java
index b45e15a..c21255f 100644
--- a/src/main/java/org/springframework/data/ldap/core/mapping/LdapPersistentProperty.java
+++ b/src/main/java/org/springframework/data/ldap/core/mapping/LdapPersistentProperty.java
@@ -48,11 +48,12 @@ public class LdapPersistentProperty extends AnnotationBasedPersistentProperty<Ld
 
 	@Override
 	protected Association<LdapPersistentProperty> createAssociation() {
-		return null;
+		throw new UnsupportedOperationException("LDAP does not support associations");
 	}
 
 	@Override
 	public boolean isIdProperty() {
 		return isId.get();
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/core/mapping/LdapSimpleTypes.java b/src/main/java/org/springframework/data/ldap/core/mapping/LdapSimpleTypes.java
index 5658942..9f9082e 100644
--- a/src/main/java/org/springframework/data/ldap/core/mapping/LdapSimpleTypes.java
+++ b/src/main/java/org/springframework/data/ldap/core/mapping/LdapSimpleTypes.java
@@ -44,4 +44,5 @@ public abstract class LdapSimpleTypes {
 	public static final SimpleTypeHolder HOLDER = new SimpleTypeHolder(VAULT_SIMPLE_TYPES, true);
 
 	private LdapSimpleTypes() {}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/core/mapping/package-info.java b/src/main/java/org/springframework/data/ldap/core/mapping/package-info.java
index 6313446..b90b78c 100644
--- a/src/main/java/org/springframework/data/ldap/core/mapping/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/core/mapping/package-info.java
@@ -1,6 +1,5 @@
 /**
  * Infrastructure for the LDAP object mapping subsystem.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.core.mapping;
diff --git a/src/main/java/org/springframework/data/ldap/repository/LdapEncoder.java b/src/main/java/org/springframework/data/ldap/repository/LdapEncoder.java
index f617ce5..108a6ca 100644
--- a/src/main/java/org/springframework/data/ldap/repository/LdapEncoder.java
+++ b/src/main/java/org/springframework/data/ldap/repository/LdapEncoder.java
@@ -49,6 +49,7 @@ public interface LdapEncoder {
 		public String encode(String value) {
 			return org.springframework.ldap.support.LdapEncoder.nameEncode(value);
 		}
+
 	}
 
 	/**
@@ -79,6 +80,7 @@ public interface LdapEncoder {
 
 			return buff.toString();
 		}
+
 	}
 
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/LdapRepository.java b/src/main/java/org/springframework/data/ldap/repository/LdapRepository.java
index 702c9a5..9086524 100644
--- a/src/main/java/org/springframework/data/ldap/repository/LdapRepository.java
+++ b/src/main/java/org/springframework/data/ldap/repository/LdapRepository.java
@@ -48,4 +48,5 @@ public interface LdapRepository<T> extends ListCrudRepository<T, Name> {
 	 * @return the entries matching the query.
 	 */
 	List<T> findAll(LdapQuery ldapQuery);
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/Query.java b/src/main/java/org/springframework/data/ldap/repository/Query.java
index b12ed59..6e8b37a 100644
--- a/src/main/java/org/springframework/data/ldap/repository/Query.java
+++ b/src/main/java/org/springframework/data/ldap/repository/Query.java
@@ -75,4 +75,5 @@ public @interface Query {
 	 * @return the count limit.
 	 */
 	int countLimit() default 0;
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryBean.java b/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryBean.java
index ccf371d..b5dcf9f 100644
--- a/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryBean.java
+++ b/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryBean.java
@@ -70,4 +70,5 @@ public class LdapRepositoryBean<T> extends CdiRepositoryBean<T> {
 	public Class<? extends Annotation> getScope() {
 		return operations.getScope();
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryExtension.java b/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryExtension.java
index d86129d..b878bc9 100644
--- a/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryExtension.java
+++ b/src/main/java/org/springframework/data/ldap/repository/cdi/LdapRepositoryExtension.java
@@ -115,4 +115,5 @@ public class LdapRepositoryExtension extends CdiRepositoryExtensionSupport {
 		return new LdapRepositoryBean<>(LdapOperations, qualifiers, repositoryType, beanManager,
 				Optional.of(getCustomImplementationDetector()));
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/cdi/package-info.java b/src/main/java/org/springframework/data/ldap/repository/cdi/package-info.java
index 90e60bc..b4824f2 100644
--- a/src/main/java/org/springframework/data/ldap/repository/cdi/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/repository/cdi/package-info.java
@@ -1,5 +1,5 @@
 /**
  * CDI support for LDAP specific repository implementation.
  */
-@org.springframework.lang.NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.repository.cdi;
diff --git a/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoriesRegistrar.java b/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoriesRegistrar.java
index 3c8b076..c6052f1 100644
--- a/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoriesRegistrar.java
+++ b/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoriesRegistrar.java
@@ -36,4 +36,5 @@ class LdapRepositoriesRegistrar extends RepositoryBeanDefinitionRegistrarSupport
 	protected RepositoryConfigurationExtension getExtension() {
 		return new LdapRepositoryConfigurationExtension();
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoryConfigurationExtension.java b/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoryConfigurationExtension.java
index 782bb59..54d7df0 100644
--- a/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoryConfigurationExtension.java
+++ b/src/main/java/org/springframework/data/ldap/repository/config/LdapRepositoryConfigurationExtension.java
@@ -112,4 +112,5 @@ public class LdapRepositoryConfigurationExtension extends RepositoryConfiguratio
 	protected boolean useRepositoryConfiguration(RepositoryMetadata metadata) {
 		return !metadata.isReactiveRepository();
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/config/package-info.java b/src/main/java/org/springframework/data/ldap/repository/config/package-info.java
index 79dacb3..4f86547 100644
--- a/src/main/java/org/springframework/data/ldap/repository/config/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/repository/config/package-info.java
@@ -1,7 +1,5 @@
 /**
  * Support infrastructure for the configuration of LDAP specific repositories.
  */
-@NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.repository.config;
-
-import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/ldap/repository/package-info.java b/src/main/java/org/springframework/data/ldap/repository/package-info.java
index 4390d1e..ec8a36a 100644
--- a/src/main/java/org/springframework/data/ldap/repository/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/repository/package-info.java
@@ -1,5 +1,5 @@
 /**
  * LDAP specific repository implementation.
  */
-@org.springframework.lang.NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.repository;
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/AbstractLdapRepositoryQuery.java b/src/main/java/org/springframework/data/ldap/repository/query/AbstractLdapRepositoryQuery.java
index 86d1fef..28f5312 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/AbstractLdapRepositoryQuery.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/AbstractLdapRepositoryQuery.java
@@ -17,6 +17,8 @@ package org.springframework.data.ldap.repository.query;
 
 import static org.springframework.data.ldap.repository.query.LdapQueryExecution.*;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.ldap.repository.Query;
 import org.springframework.data.mapping.PersistentEntity;
@@ -71,7 +73,7 @@ public abstract class AbstractLdapRepositoryQuery implements RepositoryQuery {
 
 	@Override
 	@SuppressWarnings("ConstantConditions")
-	public final Object execute(Object[] parameters) {
+	public final @Nullable Object execute(Object[] parameters) {
 
 		LdapParametersParameterAccessor parameterAccessor = new LdapParametersParameterAccessor(queryMethod, parameters);
 		LdapQuery query = createQuery(parameterAccessor);
@@ -117,4 +119,5 @@ public abstract class AbstractLdapRepositoryQuery implements RepositoryQuery {
 	public final QueryMethod getQueryMethod() {
 		return queryMethod;
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/LdapParameterAccessor.java b/src/main/java/org/springframework/data/ldap/repository/query/LdapParameterAccessor.java
index 7137d6f..543e4b6 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/LdapParameterAccessor.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/LdapParameterAccessor.java
@@ -31,4 +31,5 @@ public interface LdapParameterAccessor extends ParameterAccessor {
 	 * @return
 	 */
 	Object[] getBindableParameterValues();
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/LdapParameters.java b/src/main/java/org/springframework/data/ldap/repository/query/LdapParameters.java
index 3186324..ee99baa 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/LdapParameters.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/LdapParameters.java
@@ -18,6 +18,8 @@ package org.springframework.data.ldap.repository.query;
 import java.lang.reflect.Method;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.MethodParameter;
 import org.springframework.data.geo.Distance;
@@ -27,7 +29,6 @@ import org.springframework.data.repository.query.Parameter;
 import org.springframework.data.repository.query.Parameters;
 import org.springframework.data.repository.query.ParametersSource;
 import org.springframework.data.util.TypeInformation;
-import org.springframework.lang.Nullable;
 
 /**
  * Custom extension of {@link Parameters} discovering additional
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryCreator.java b/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryCreator.java
index 6392a44..6dcb3bf 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryCreator.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryCreator.java
@@ -15,11 +15,11 @@
  */
 package org.springframework.data.ldap.repository.query;
 
-import static org.springframework.ldap.query.LdapQueryBuilder.*;
-
 import java.util.Iterator;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.mapping.PropertyPath;
@@ -73,7 +73,7 @@ class LdapQueryCreator extends AbstractQueryCreator<LdapQuery, ContainerCriteria
 
 		Entry entry = AnnotatedElementUtils.findMergedAnnotation(entityType, Entry.class);
 
-		LdapQueryBuilder query = query();
+		LdapQueryBuilder query = LdapQueryBuilder.query();
 
 		if (entry != null) {
 			query = query.base(entry.base());
@@ -148,7 +148,8 @@ class LdapQueryCreator extends AbstractQueryCreator<LdapQuery, ContainerCriteria
 	}
 
 	@Override
-	protected LdapQuery complete(ContainerCriteria criteria, Sort sort) {
-		return criteria;
+	protected LdapQuery complete(@Nullable ContainerCriteria criteria, Sort sort) {
+		return criteria == null ? LdapQueryBuilder.query() : criteria;
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryExecution.java b/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryExecution.java
index 5e87286..2ab06b8 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryExecution.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryExecution.java
@@ -15,6 +15,8 @@
  */
 package org.springframework.data.ldap.repository.query;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.data.convert.DtoInstantiatingConverter;
@@ -39,6 +41,7 @@ import org.springframework.util.ClassUtils;
 @FunctionalInterface
 interface LdapQueryExecution {
 
+	@Nullable
 	Object execute(LdapQuery query);
 
 	/**
@@ -57,13 +60,14 @@ interface LdapQueryExecution {
 		}
 
 		@Override
-		public Object execute(LdapQuery query) {
+		public @Nullable Object execute(LdapQuery query) {
 			try {
 				return operations.findOne(query, entityType);
 			} catch (EmptyResultDataAccessException e) {
 				return null;
 			}
 		}
+
 	}
 
 	/**
@@ -85,6 +89,7 @@ interface LdapQueryExecution {
 		public Object execute(LdapQuery query) {
 			return operations.find(query, entityType);
 		}
+
 	}
 
 	/**
@@ -108,6 +113,7 @@ interface LdapQueryExecution {
 		public Object execute(LdapQuery query) {
 			return operations.find(query, entityType).stream().map(resultProcessing::convert);
 		}
+
 	}
 
 	/**
@@ -124,9 +130,12 @@ interface LdapQueryExecution {
 		}
 
 		@Override
-		public Object execute(LdapQuery query) {
-			return converter.convert(delegate.execute(query));
+		public @Nullable Object execute(LdapQuery query) {
+
+			Object result = delegate.execute(query);
+			return result != null ? converter.convert(result) : null;
 		}
+
 	}
 
 	/**
@@ -149,7 +158,7 @@ interface LdapQueryExecution {
 		}
 
 		@Override
-		public Object convert(Object source) {
+		public @Nullable Object convert(@Nullable Object source) {
 
 			ReturnedType returnedType = processor.getReturnedType();
 
@@ -165,5 +174,7 @@ interface LdapQueryExecution {
 
 			return processor.processResult(source, converter);
 		}
+
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryMethod.java b/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryMethod.java
index a5b1c87..4f7e89f 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryMethod.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/LdapQueryMethod.java
@@ -17,12 +17,13 @@ package org.springframework.data.ldap.repository.query;
 
 import java.lang.reflect.Method;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.data.ldap.repository.Query;
 import org.springframework.data.projection.ProjectionFactory;
 import org.springframework.data.repository.core.RepositoryMetadata;
 import org.springframework.data.repository.query.QueryMethod;
-import org.springframework.lang.Nullable;
 
 /**
  * QueryMethod for Ldap Queries.
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/PartTreeLdapRepositoryQuery.java b/src/main/java/org/springframework/data/ldap/repository/query/PartTreeLdapRepositoryQuery.java
index dd08c46..eb608fe 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/PartTreeLdapRepositoryQuery.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/PartTreeLdapRepositoryQuery.java
@@ -74,4 +74,5 @@ public class PartTreeLdapRepositoryQuery extends AbstractLdapRepositoryQuery {
 				getEntityClass(), objectDirectoryMapper, parameters, inputProperties);
 		return queryCreator.createQuery();
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/StringBasedQuery.java b/src/main/java/org/springframework/data/ldap/repository/query/StringBasedQuery.java
index 2499f0d..f5d12be 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/StringBasedQuery.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/StringBasedQuery.java
@@ -27,6 +27,8 @@ import java.util.function.Function;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.data.expression.ValueExpression;
 import org.springframework.data.expression.ValueExpressionParser;
 import org.springframework.data.repository.query.Parameter;
@@ -34,7 +36,6 @@ import org.springframework.data.repository.query.ParameterAccessor;
 import org.springframework.data.repository.query.Parameters;
 import org.springframework.data.repository.query.ValueExpressionDelegate;
 import org.springframework.data.spel.ExpressionDependencies;
-import org.springframework.lang.Nullable;
 import org.springframework.ldap.support.LdapEncoder;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -245,6 +246,7 @@ class StringBasedQuery {
 
 			return (matcherMap.isEmpty() ? null : matcherMap.values().iterator().next());
 		}
+
 	}
 
 	/**
@@ -288,6 +290,7 @@ class StringBasedQuery {
 
 			return result.append(input.subSequence(currentPosition, input.length())).toString();
 		}
+
 	}
 
 	/**
@@ -349,8 +352,7 @@ class StringBasedQuery {
 		 * @param binding must not be {@literal null}.
 		 * @return the value used for the given {@link ParameterBinding}.
 		 */
-		@Nullable
-		private Object getParameterValueForBinding(ParameterBinding binding) {
+		private @Nullable Object getParameterValueForBinding(ParameterBinding binding) {
 
 			if (binding.isExpression()) {
 				return evaluator.apply(binding.getRequiredExpression());
@@ -439,6 +441,9 @@ class StringBasedQuery {
 
 				return parameterName;
 			}
+
 		}
+
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/query/package-info.java b/src/main/java/org/springframework/data/ldap/repository/query/package-info.java
index a943040..42a4503 100644
--- a/src/main/java/org/springframework/data/ldap/repository/query/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/repository/query/package-info.java
@@ -1,7 +1,5 @@
 /**
  * Query derivation mechanism for LDAP specific repositories.
  */
-@NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.repository.query;
-
-import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/DefaultLdapAnnotationProcessorConfiguration.java b/src/main/java/org/springframework/data/ldap/repository/support/DefaultLdapAnnotationProcessorConfiguration.java
index 73539e2..5f2f838 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/DefaultLdapAnnotationProcessorConfiguration.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/DefaultLdapAnnotationProcessorConfiguration.java
@@ -22,7 +22,8 @@ import javax.annotation.processing.ProcessingEnvironment;
 import javax.annotation.processing.RoundEnvironment;
 import javax.lang.model.element.VariableElement;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.ldap.odm.annotations.Id;
 
 import com.querydsl.apt.DefaultConfiguration;
@@ -55,4 +56,5 @@ class DefaultLdapAnnotationProcessorConfiguration extends DefaultConfiguration {
 	public boolean isValidField(VariableElement field) {
 		return super.isValidField(field) && field.getAnnotation(Id.class) == null;
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/LdapAnnotationProcessor.java b/src/main/java/org/springframework/data/ldap/repository/support/LdapAnnotationProcessor.java
index 7444390..4d290b4 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/LdapAnnotationProcessor.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/LdapAnnotationProcessor.java
@@ -53,4 +53,5 @@ public class LdapAnnotationProcessor extends AbstractQuerydslProcessor {
 
 		return configuration;
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/LdapEntityInformation.java b/src/main/java/org/springframework/data/ldap/repository/support/LdapEntityInformation.java
index d291072..4a32c2f 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/LdapEntityInformation.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/LdapEntityInformation.java
@@ -18,8 +18,9 @@ package org.springframework.data.ldap.repository.support;
 
 import javax.naming.Name;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.data.repository.core.support.AbstractEntityInformation;
-import org.springframework.lang.Nullable;
 import org.springframework.ldap.odm.core.ObjectDirectoryMapper;
 
 /**
@@ -39,9 +40,8 @@ class LdapEntityInformation<T> extends AbstractEntityInformation<T, Name> {
 		this.odm = odm;
 	}
 
-	@Nullable
 	@Override
-	public Name getId(T entity) {
+	public @Nullable Name getId(T entity) {
 		return odm.getId(entity);
 	}
 
@@ -49,4 +49,5 @@ class LdapEntityInformation<T> extends AbstractEntityInformation<T, Name> {
 	public Class<Name> getIdType() {
 		return Name.class;
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactory.java b/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactory.java
index 838cffe..d68ddfd 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactory.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactory.java
@@ -22,6 +22,8 @@ import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 import java.util.Optional;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.ldap.core.mapping.LdapMappingContext;
 import org.springframework.data.ldap.repository.query.AnnotatedLdapRepositoryQuery;
@@ -149,7 +151,7 @@ public class LdapRepositoryFactory extends RepositoryFactorySupport {
 	}
 
 	@Override
-	protected Optional<QueryLookupStrategy> getQueryLookupStrategy(Key key,
+	protected Optional<QueryLookupStrategy> getQueryLookupStrategy(@Nullable Key key,
 			ValueExpressionDelegate valueExpressionDelegate) {
 		return Optional
 				.of(new LdapQueryLookupStrategy(ldapOperations, instantiators, mappingContext, valueExpressionDelegate));
@@ -199,5 +201,7 @@ public class LdapRepositoryFactory extends RepositoryFactorySupport {
 				return new PartTreeLdapRepositoryQuery(queryMethod, domainType, ldapOperations, mappingContext, instantiators);
 			}
 		}
+
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactoryBean.java b/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactoryBean.java
index c5c94bf..653535d 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactoryBean.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/LdapRepositoryFactoryBean.java
@@ -17,6 +17,8 @@ package org.springframework.data.ldap.repository.support;
 
 import javax.naming.Name;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.data.ldap.core.mapping.LdapMappingContext;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
@@ -24,7 +26,6 @@ import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.repository.Repository;
 import org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport;
 import org.springframework.data.repository.core.support.RepositoryFactorySupport;
-import org.springframework.lang.Nullable;
 import org.springframework.ldap.core.LdapOperations;
 import org.springframework.util.Assert;
 
@@ -87,4 +88,5 @@ public class LdapRepositoryFactoryBean<T extends Repository<S, Name>, S>
 			setMappingContext(new LdapMappingContext());
 		}
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/LdapSerializer.java b/src/main/java/org/springframework/data/ldap/repository/support/LdapSerializer.java
index c193aea..d2462f5 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/LdapSerializer.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/LdapSerializer.java
@@ -126,4 +126,5 @@ class LdapSerializer implements Visitor<Object, Void> {
 	public Object visit(TemplateExpression<?> expr, Void context) {
 		throw new UnsupportedOperationException();
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapPredicateExecutor.java b/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapPredicateExecutor.java
index 187544a..0c4bed6 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapPredicateExecutor.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapPredicateExecutor.java
@@ -26,6 +26,8 @@ import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.convert.DtoInstantiatingConverter;
 import org.springframework.data.domain.Example;
@@ -43,7 +45,6 @@ import org.springframework.data.querydsl.QuerydslPredicateExecutor;
 import org.springframework.data.repository.core.EntityInformation;
 import org.springframework.data.repository.query.FluentQuery;
 import org.springframework.data.support.PageableExecutionUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.ldap.core.LdapOperations;
 import org.springframework.ldap.query.LdapQueryBuilder;
 import org.springframework.util.Assert;
@@ -247,9 +248,8 @@ public class QuerydslLdapPredicateExecutor<T> implements ListQuerydslPredicateEx
 			return new FluentQuerydsl<>(predicate, sort, resultType, new ArrayList<>(properties));
 		}
 
-		@Nullable
 		@Override
-		public R oneValue() {
+		public @Nullable R oneValue() {
 
 			List<T> results = findTop(2);
 
@@ -265,9 +265,8 @@ public class QuerydslLdapPredicateExecutor<T> implements ListQuerydslPredicateEx
 			return getConversionFunction().apply(one);
 		}
 
-		@Nullable
 		@Override
-		public R firstValue() {
+		public @Nullable R firstValue() {
 
 			List<T> results = findTop(2);
 
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapQuery.java b/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapQuery.java
index b3381bf..441fc6c 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapQuery.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/QuerydslLdapQuery.java
@@ -133,4 +133,5 @@ public class QuerydslLdapQuery<K> implements FilteredClause<QuerydslLdapQuery<K>
 
 		return where != null ? builder.filter(filterGenerator.handle(where)) : builder.filter(new AbsoluteTrueFilter());
 	}
+
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/SimpleLdapRepository.java b/src/main/java/org/springframework/data/ldap/repository/support/SimpleLdapRepository.java
index 0ac4534..ff061a0 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/SimpleLdapRepository.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/SimpleLdapRepository.java
@@ -24,6 +24,8 @@ import java.util.stream.StreamSupport;
 
 import javax.naming.Name;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.data.domain.Persistable;
 import org.springframework.data.ldap.repository.LdapRepository;
@@ -31,7 +33,6 @@ import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.util.Optionals;
-import org.springframework.lang.Nullable;
 import org.springframework.ldap.NameNotFoundException;
 import org.springframework.ldap.core.LdapOperations;
 import org.springframework.ldap.core.support.CountNameClassPairCallbackHandler;
@@ -227,16 +228,8 @@ public class SimpleLdapRepository<T> implements LdapRepository<T> {
 		return ldapOperations.find(ldapQuery, entityType);
 	}
 
-
 	private <S extends T> boolean isNew(S entity, @Nullable Name id) {
-
-		if (entity instanceof Persistable) {
-			Persistable<?> persistable = (Persistable<?>) entity;
-			return persistable.isNew();
-		} else {
-			return id == null;
-		}
+		return entity instanceof Persistable<?> p ? p.isNew() : id == null;
 	}
 
-
 }
diff --git a/src/main/java/org/springframework/data/ldap/repository/support/package-info.java b/src/main/java/org/springframework/data/ldap/repository/support/package-info.java
index b7b4cd0..6a32679 100644
--- a/src/main/java/org/springframework/data/ldap/repository/support/package-info.java
+++ b/src/main/java/org/springframework/data/ldap/repository/support/package-info.java
@@ -1,7 +1,5 @@
 /**
  * Support infrastructure for query derivation of LDAP specific repositories.
  */
-@NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.ldap.repository.support;
-
-import org.springframework.lang.NonNullApi;