https://issues.jenkins.io/browse/JENKINS-65156 adds a trait to ignore draft PR. However when a PR is eventually set to ready for review, the PR is not updated until Branch Indexing kicks off. GitHub Branch Source should support the proper Webhook event action and act accordingly. So that PR jobs are automatically updated / considered.

How to Reproduce

• create a Multibranch that scan PRs and ignore Draft PRs (using the "Ignore pull requests marked as drafts" trait)

Then focus on a scanned PR

• change the PR to draft in GitHub, nothing happens... (unexpected)
• trigger branch indexing, the PR is not marked as dead (expected)
• change the PR to ready for review in Github, nothing happens (unexpected)
• trigger branch indexing, the PR is not active again (expected)