After navigating through the internet I’ve finally found some info from one of the developers themselves. I wish they would have been more clear on the basics in the documentation.
Quote:
Binding adapters are annotated methods in any class that are used to do just this. Typically, you’d organize your adapters into [-a] classes based on the target View type.
This obviously means that at compile time all methods in any class with the annotation BindingAdapter will generate the BindingAdapter.