As of a sudden, jenkins jobs for pull requests are not triggered anymore but rather get the following output in the job log:

Branch event
java.lang.NullPointerException
Finished: FAILURE

Steps to reproduce

• In Bitbucket:
  Ensure that Webhook to Jenkins for Bitbucket Server is setup to trigger builds in Jenkins
• In Jenkins:
  Setup "Bitbucket Team Folder"
• Create a branch in Bitbucket
• Commit and push some changes -> jenkins job for branch is created and successfully run
• Create a PR

Expected:

• A jenkins job for the PR is created
• The jenkins job runs successfully

Actual:

• A jenkins job for the PR is created
• The jenkins job fails immediately with the message mentioned above