How to debug with flutter_workmanager

Question

I created a simple server to log the time API was called. I fork code of flutter_workmanager and then set frequency 15 to call API, I turn off the phone screen and wait 15 minutes but no query call to my server. Are there any alternative methods to address this particular case? Thank you. I'm just forking and modifying the WorkManager library. Here is my code: gist.github.com/nk4n01/ca8155c9afbf47677c4c95d39884592e