title: Jenkins 2 Job: process only changed files from download
body: <p>I have a Jenkins 2 Pipeline job which downloads a file and performs some processings. The job is triggered periodically, so sometimes the downloaded file has not changed.</p>
  
  <p>The question is now: how can I check if the file has changed from the last run to stop and avoid the processing? As an additional difficulty the name of the file changes on every download :-(</p>
  
  <p>Kind regards, Christian</p>