I am looking for the method of pulling JSON elements from the webhook request in a jenkins multibranch pipeline build, which is orchestrated by a Jenkinsfile using declarative pipeline syntax. (The regular Jenkins pipeline job has a "Generic Webhook trigger" section where you use JSONPATH to map incoming JSON elements into variables, but the multibranch pipeline seems not to have this.)
I am triggering (successfully) a pull-request build from Azure DevOps, and I need the pull request # from the JSON so I can signal back to Azure whether the build was successful or not. Thanks in advance.