Databinding libraries are being refactored as a part of androidx refactoring.
I found the databinding annotation processor dependency link from google’s maven repository here.
I’ve constructed the actual gradle dependency from there.
kapt "androidx.databinding:databinding-compiler:3.2.0-alpha16"
Update
As of Android studio 3.2.0-beta01, databinding no longer needs its annotation processor dependency to be declared in the gradle file, since databinding is capable of resolving its dependency.