Android/libs/ is empty

There is a problem with gradle(w) wrapper, where it keeps changing from distributionUrl=http\://services.gradle.org/distributions/gradle-2.14.1-all.zip to distributionUrl=http\://services.gradle.org/distributions/gradle-2.13-all.zip. In the task wrapper(type:Wrapper){ gradleVersion='2.14.1' }, but still nothing seems to change.

Someone suggested in the android/libs/builders/GradleBuilder.js, change this line 'var distributionUrl = process.env[‘CORDOVA_ANDROID_GRADLE_DISTRIBUTION_URL’] || ‘http\://services.gradle.org/distributions/gradle-2.13-all.zip’;. But in my current folder,android/libs/` is empty. Does this seem right?

Platforms used cordova android 5.2.2, cordova android 5.1.1 and cordova android 5.2.1.

Nvm, found the solution. It is android/cordova/libs/builders/GradleBuilder.js.