Is ext.deps in buiild.gradle really needed?

[mobilekosmos]

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I'm wondering what this block is needed for? I deleted it and the project builds anyways, and as an Android Dev I also don't know this, thankful about clarifications.

ext.deps = [
                android: [
                        'runtime'     : 'com.google.android:android:4.1.1.4',
                        'gradlePlugin': "com.android.tools.build:gradle:${versions.androidPlugin}",
                ]
        ]