Use Spring nullability annotations instead of JSR305.

Closes #2239.

src/main/java/org/springframework/data/jpa/repository/query/NativeJpaQuery.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.data.jpa.repository.query;
 
-import javax.annotation.Nullable;
 import javax.persistence.EntityManager;
 import javax.persistence.Query;
 import javax.persistence.Tuple;
@@ -25,6 +24,7 @@ import org.springframework.data.repository.query.QueryMethodEvaluationContextPro
 import org.springframework.data.repository.query.RepositoryQuery;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link RepositoryQuery} implementation that inspects a {@link org.springframework.data.repository.query.QueryMethod}

src/main/java/org/springframework/data/jpa/repository/support/QuerydslRepositorySupport.java

@@ -15,11 +15,11 @@
  */
 package org.springframework.data.jpa.repository.support;
 
-import javax.annotation.Nullable;
 import javax.annotation.PostConstruct;
 import javax.persistence.EntityManager;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Repository;
 import org.springframework.util.Assert;
 

src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -30,6 +30,7 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Stream;
 
@@ -46,6 +47,7 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.DataIntegrityViolationException;
@@ -59,7 +61,6 @@ import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Slice;
 import org.springframework.data.domain.Sort;
-import org.springframework.data.domain.ExampleMatcher.*;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.domain.Sort.Order;
 import org.springframework.data.jpa.domain.Specification;
@@ -67,14 +68,13 @@ import org.springframework.data.jpa.domain.sample.Address;
 import org.springframework.data.jpa.domain.sample.Role;
 import org.springframework.data.jpa.domain.sample.SpecialUser;
 import org.springframework.data.jpa.domain.sample.User;
-import org.springframework.data.jpa.repository.sample.UserRepository;
 import org.springframework.data.jpa.repository.sample.SampleEvaluationContextExtension.SampleSecurityContextHolder;
+import org.springframework.data.jpa.repository.sample.UserRepository;
 import org.springframework.data.jpa.repository.sample.UserRepository.NameOnly;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 import org.springframework.transaction.annotation.Transactional;
 
-import com.google.common.base.Optional;
 
 /**
  * Base integration test class for {@code UserRepository}. Loads a basic (non-namespace) Spring configuration file as

src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java

@@ -19,6 +19,7 @@ import java.util.Collection;
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Stream;
 
@@ -42,8 +43,6 @@ import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.query.Param;
 import org.springframework.transaction.annotation.Transactional;
 
-import com.google.common.base.Optional;
-
 /**
  * Repository interface for {@code User}s.
  *