Steps to replicate:

1. Did setup - installing plugin, giving bitbucket instance details with a token in Jenkins --> Manage Jenkins --> Configure System --> Bitbucket Server integration
2. Created a multi-configuration job and linked with bitbucket repo of master branch to get the code
3. Create branch(Ex: dev_branch) from a master in the repo and commit any change to the dev_branch

Actual:

Job is getting triggered by taking master branch code

Expected:

The job should trigger only if there is any new commit to master. However, the job is running for commit made due to dev_branch.
Running a job with master code even though there are no new changes is not worth it.

If I select dev_branch in the Job then it should poll for new commits to that branch and trigger.