Fix for bulk saving multiple auto id entitites

Author: JohannesRabauer

spring-data-eclipse-store/src/main/java/software/xdev/spring/data/eclipse/store/repository/support/id/IdManager.java

@@ -147,7 +147,7 @@ public <S extends T> void checkIds(final Collection<S> entities)
 		}
 
 		final List<ID> multipleEqualIds = ids.stream()
-			.filter(id -> Collections.frequency(ids, id) > 1)
+			.filter(id -> id != null && Collections.frequency(ids, id) > 1)
 			.toList();
 		if(!multipleEqualIds.isEmpty())
 		{

spring-data-eclipse-store/src/main/java/software/xdev/spring/data/eclipse/store/repository/support/id/SimpleIdSetter.java

@@ -61,7 +61,7 @@ public void ensureId(final T objectToSetIdIn)
 			final Object existingId = fam.getValueOfField(objectToSetIdIn);
 			if(existingId == null)
 			{
-				final ID newId = (ID)this.idFinder.findId();
+				final ID newId = this.idFinder.findId();
 				fam.writeValueOfField(objectToSetIdIn, newId, true);
 				this.lastIdPersister.accept(newId);
 			}

spring-data-eclipse-store/src/test/java/software/xdev/spring/data/eclipse/store/integration/isolated/tests/id/IdTest.java

@@ -75,6 +75,29 @@ void testCreateSingleWithAutoIdInteger(@Autowired final CustomerWithIdIntegerRep
 		);
 	}
 
+	@Test
+	void saveBulkWithAutoIdInteger(@Autowired final CustomerWithIdIntegerRepository customerRepository)
+	{
+		final CustomerWithIdInteger customer1 = new CustomerWithIdInteger(TestData.FIRST_NAME, TestData.LAST_NAME);
+		final CustomerWithIdInteger customer2 = new CustomerWithIdInteger(TestData.FIRST_NAME, TestData.LAST_NAME);
+		customerRepository.saveAll(List.of(customer1, customer2));
+		
+		TestUtil.doBeforeAndAfterRestartOfDatastore(
+			this.configuration,
+			() -> {
+				Assertions.assertEquals(2, customerRepository.count());
+				
+				final Optional<CustomerWithIdInteger> loadedCustomer1 = customerRepository.findById(0);
+				Assertions.assertTrue(loadedCustomer1.isPresent());
+				Assertions.assertEquals(customer1, loadedCustomer1.get());
+				
+				final Optional<CustomerWithIdInteger> loadedCustomer2 = customerRepository.findById(1);
+				Assertions.assertTrue(loadedCustomer2.isPresent());
+				Assertions.assertEquals(customer2, loadedCustomer2.get());
+			}
+		);
+	}
+	
 	/**
 	 * In other tests {@link EclipseStoreStorage#clearData} is called. Here the datastore is restarted again to ensure
 	 * no previous method is called before the test.