Note: if you would like to change the visible Package ID of Headwind MDM launcher, you DO NOT NEED to change the Java package ID in a whole source code! This will most probably stop you from getting further updates by merging your code with the main repository!
What you need to do is to change the applicationId in app/build.gradle and package in AndroidManifest.xml.
The package ID can be changed using Gradle build variants (flavors). Please take a look at sweetlife and aqualine build variants in app/build.gradle, you will see how it is done.