We noticed that WebhookEvents are not removed if the waitForQualityGate step is executed after analysis is already completed. This caused one of our Jenkins instances to run out of memory.

Is seems like  org.sonarsource.scanner.jenkins.pipeline.WaitForQualityGateStep.Execution#checkTaskCompleted() should remove the WebhookEvents if the analysis is complete.

https://github.com/SonarSource/sonar-scanner-jenkins/blob/sonar-2.17.2/src/main/java/org/sonarsource/scanner/jenkins/pipeline/WaitForQualityGateStep.java#L179

https://github.com/SonarSource/sonar-scanner-jenkins/blob/sonar-2.17.1/src/main/java/org/sonarsource/scanner/jenkins/pipeline/WaitForQualityGateStep.java#L238