title: how to get current selected product flavors in app/build.gradle file
body: <p>Example, I have area1 and area2 flavors, but just area2 have google gms dependency, and I just want apply gms plugin to area2, so I need decide
  current flavors as <code>area == 'area2'</code>, obvious this can't succeed, so how can I to do ?</p>
  
  <pre><code>flavorDimensions "area"
  productFlavors {
      area1 {
          dimension "area"
          applicationId 'com.sample.area1'
      }
      area2 {
          dimension "area"
          applicationId 'com.sample.area2'
      }
  }
  dependencies {
     area2Implementation 'com.google.android.gms:play-services-auth: 16.0.1'
  }
  if(area == 'area2') {
    apply plugin: 'com.google.gms.google-services'
  }
  </code></pre>