Unity vs Android Gradle Version

When use "Gradle" build system in android, plugin's mainTemplate gradle file should be include following classpath in dependiencies phrase.

//5.6.3, 2017.1 and 2017.2 : Android plugin version 2.1.0, Gradle version 2.14.

      classpath 'com.android.tools.build:gradle:2.1.0'

//2017.4 and 2018.1 : Android plugin version 2.3.0, Gradle version 4.0.1.

      classpath 'com.android.tools.build:gradle:2.3.0'

//2018.2 : Android plugin version 3.0.1, Gradle version 4.2.1.

      classpath 'com.android.tools.build:gradle:3.0.1'

//2018.3 : Android plugin version 3.2.0, Gradle version 4.6.

      classpath 'com.android.tools.build:gradle:3.2.0'