abstracting gradle plugin version across multiple files

build.gradle

//https://medium.com/@StefMa/its-time-to-ditch-the-buildscript-block-a1ab12e0d9ce
pluginManagement { 
  repositories { ... }
  eachPlugin { 
    if (requested.id.id.startsWith("com.android")) {
      useModule("com.android.tools.build:gradle:3.1.1")
    }
    if (requested.id.id.startsWith("org.jetbrains.kotlin")) {
      useVersion("1.2.31")
    }
  } 
}