Android - specifying product flavor and build type for Gradle dependencies

I'm trying to define a dependency that will exist on my beta flavor builds, on both debug and release, but never on my production builds. I was following some examples that I saw online and the syntax made sense, but it seems to NOT be working for me. Here's what I have in a nutshell:

  productFlavors {
        beta {
        }

        prod {
        }
    }
  


dependencies {

    betaDebugImplementation XYZ // this doesn't work.
}

The error I get is this one: > Could not find method betaDebugImplementation() .

Did I miss some step?