Leniently accept null when calling delete(Specification).

Closes #2796

Author: mp911de

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

@@ -15,12 +15,7 @@
  */
 package org.springframework.data.jpa.repository.support;
 
-import static org.springframework.data.jpa.repository.query.QueryUtils.COUNT_QUERY_STRING;
-import static org.springframework.data.jpa.repository.query.QueryUtils.DELETE_ALL_QUERY_BY_ID_STRING;
-import static org.springframework.data.jpa.repository.query.QueryUtils.DELETE_ALL_QUERY_STRING;
-import static org.springframework.data.jpa.repository.query.QueryUtils.applyAndBind;
-import static org.springframework.data.jpa.repository.query.QueryUtils.getQueryString;
-import static org.springframework.data.jpa.repository.query.QueryUtils.toOrders;
+import static org.springframework.data.jpa.repository.query.QueryUtils.*;
 
 import jakarta.persistence.EntityManager;
 import jakarta.persistence.LockModeType;
@@ -524,10 +519,12 @@ public long delete(Specification<T> spec) {
 		CriteriaBuilder builder = this.em.getCriteriaBuilder();
 		CriteriaDelete<T> delete = builder.createCriteriaDelete(getDomainClass());
 
-		Predicate predicate = spec.toPredicate(delete.from(getDomainClass()), null, builder);
+		if (spec != null) {
+			Predicate predicate = spec.toPredicate(delete.from(getDomainClass()), null, builder);
 
-		if (predicate != null) {
-			delete.where(predicate);
+			if (predicate != null) {
+				delete.where(predicate);
+			}
 		}
 
 		return this.em.createQuery(delete).executeUpdate();

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

@@ -609,6 +609,16 @@ void returnsSamePageIfNoSpecGiven() {
 		assertThat(repository.findAll((Specification<User>) null, pageable)).isEqualTo(repository.findAll(pageable));
 	}
 
+	@Test // GH-2796
+	void removesAllIfSpecificationIsNull() {
+
+		flushTestUsers();
+
+		repository.delete((Specification<User>) null);
+
+		assertThat(repository.count()).isEqualTo(0L);
+	}
+
 	@Test
 	void returnsAllAsPageIfNoPageableIsGiven() {