How avoiding optimization of unused classes in android

Question

There is reflection usage in my project sub-module, but the final compiled dex file will not contain this unused class when some lines of code are deleted, and it can be compiled into dex after adding one line of code. There is also a phenomenon that when this module is dependent on other modules, other modules can be normally referenced in the Android Studio, but an error that the class cannot be found occurs during the build process. It needs to be stated that no optimization or obfuscation configuration is turned on in the project. Has anyone encountered this type of problem? Or provide some suggestions, thanks.