apollo-kotlin: Could not set unknown property 'generateClasses' for object of type com.apollographql.android.gradle.ApolloExtension.

Guys, I probably just being stupid, but I think it is a bug! I’m trying to get apollo-client generates classes, I tried to force it with apollo { generateClasses = true } but I am getting this error: Could not set unknown property 'generateClasses' for object of type com.apollographql.android.gradle.ApolloExtension.

here is my project/build.gradle

buildscript {
    repositories {
        jcenter()
        maven { url "https://jitpack.io" }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.1'
        classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8' // Dagger
        classpath "io.realm:realm-gradle-plugin:2.3.1" // Realm

        classpath 'com.apollographql.android:gradle-plugin:0.2.2'

    }
}

allprojects {
    repositories {
        jcenter()
        maven { url "https://jitpack.io" }
    }
}

and this is my app/build.gradle

apply plugin: 'com.android.application'
apply plugin: 'com.apollographql.android'
...

apollo {
    generateClasses = true
}

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.0"
   ...
}

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.android.support:appcompat-v7:25.1.1'
    ...
}

I can’t see where I am wrong. Please help me here, what am I doing wrong?