Error building the androidEmptyExample

Ok, I've done as you have said.

• I've copied the build.gradle file from OF/examples/android/androidEmptyExample to OF/examples/android/androidPolygonExample.

• I've edited the file OF/openFrameworks/blob/master/libs/openFrameworksCompiled/project/android/settings.gradle adding include 'examples:android:androidPolygonExample' . (I assume that everytime i want to try a different example i will have to edit the same file, right?)

• I've resynced the project, but the sync fails with this error:
  Plugin with id 'com.android.application' not found.

Probably because of some missing dependencies. I've added these lines to my

build.gradle file
buildscript {
    repositories {
        mavenCentral() // or jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:1.3.1'
    }
}

as suggested here:

But the sync still fails because of this error
Project with path ':ofAndroidLib' could not be found in root project 'androidPolygonExample'.