[KAFKA-13139] Empty response after requesting to restart a connector without the tasks results in NPE

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 3.0.0
• Component/s: KafkaConnect
• Assignee: Konstantine Karantasis
• Reporter: Konstantine Karantasis
• Created: 26/Jul/21 19:58
• Updated: 27/Jul/21 22:33
• Resolved: 27/Jul/21 21:00

Description

After https://issues.apache.org/jira/browse/KAFKA-4793 a response to restart only the connector (without any tasks) returns OK with an empty body. 

As system test runs revealed, this causes an NPE in https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/rest/RestClient.java#L135

We should return 204 (NO_CONTENT) instead. 

This is a regression from previous behavior, therefore the ticket is marked as a blocker candidate for 3.0

Issue Links

• links to: GitHub Pull Request #11132