How to define different dependencies for different product flavors

I am converting one of my apps to Gradle and would like to use the new build flavor features to have a paid and a free ad based flavor.

I want only the ad based version to depend on the admob SDK.

My build file looks like this:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.5.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 18
    buildToolsVersion "18.0.1"

    defaultConfig {
        minSdkVersion 10
        targetSdkVersion 18
    }

    productFlavors {
        Pro {
            packageName "de.janusz.journeyman.zinsrechner.pro"
        }
        Free { 
            dependencies {

            }
        }
    }
}

dependencies {
    compile 'com.android.support:support-v4:18.0.+'
    compile 'com.actionbarsherlock:actionbarsherlock:4.4.0@aar'
    compile fileTree(dir: 'libs', include: '*.jar')
}

Is there a way to configure the dependency in the free product flavor to have its own libs folder that is merged with the main libs folder that contains general libraries for both flavors?

If this is possible how would I define this folder?

To define a flavor specific dependency you can use proCompile instead of compile in your dependency section. When you run gradle properties you get an overview of automatic created configurations.

The correct build file looks like this:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'
    }
}
apply plugin: 'com.android.application'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        minSdkVersion 10
        targetSdkVersion 22
    }

    productFlavors {
        pro {
            packageName "de.janusz.journeyman.zinsrechner.pro"
        }
        free { }
    }
}

dependencies {
    compile 'com.android.support:support-v4:22.2.0'
    freeCompile 'com.google.android.gms:play-services-ads:7.5.0'
}