Use empty iterator instead of null

Signed-off-by: Stefano Cordio <[email protected]>

Author: scordio

spring-batch-notion/src/main/java/org/springframework/batch/extensions/notion/NotionDatabaseItemReader.java

@@ -32,6 +32,7 @@
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.util.Assert;
 
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -180,7 +181,7 @@ public void setPageSize(int pageSize) {
 	@Override
 	protected Iterator<T> doPageRead() {
 		if (!hasMore) {
-			return null;
+			return Collections.emptyIterator();
 		}
 
 		QueryDatabaseRequest request = new QueryDatabaseRequest(databaseId);