[COLLECTIONS-756] CollectionUtils.filter(..) broken with blank Collections.singleton

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 4.4
• Component/s: Collection
• Assignee: Unassigned
• Reporter: noname713705
• Created: 08/Mar/20 22:20
• Updated: 08/Mar/20 23:29
• Resolved: 08/Mar/20 23:29

Description

When using CollectionUtils.filter(..), if the passed collection is initialized with jdk Collections.singleton(..) and only contains an isBlank(..) string, the method will throw an exception instead of removing blank item as expected. Tested with commons-collections:4.4 and java8.

All can be resumed with

CollectionUtils.filter(Collections.singleton(" "), StringUtils::isNotBlank);