[FLINK-30864] Optional pattern at the start of a group pattern not working

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.15.3, 1.16.1
• Fix Version/s: 1.17.0, 1.15.4, 1.16.2
• Component/s: Library / CEP
• Labels: pull-request-available
• Assignee: Juntao Hu
• Reporter: Juntao Hu
• Created: 01/Feb/23 11:25
• Updated: 17/Feb/23 07:44
• Resolved: 15/Feb/23 01:40

Description

The optional pattern at the start of a group pattern turns out be "not optional", e.g.

Pattern.<String>begin("A").next(Pattern.<String>begin("B").optional().next("C")).next("D")

cannot match sequence "a1 c1 d1".

Issue Links

• links to: GitHub Pull Request #21866
• links to: GitHub Pull Request #21930
• links to: GitHub Pull Request #21931