Android Gradle - Add packageNameSuffix on specific productFlavor

I have a Gradle Android Project with this product Groups and Flavors configuration:

/*
 * Define different flavor groups
 */
flavorGroups 'market', 'version'

/*
 * Defile product flavors
 */
productFlavors {

    amazon {
        flavorGroup 'market'
    }

    google {
        flavorGroup 'market'
    }

    flav1 {
        flavorGroup 'version'
        packageName 'com.company.flav1'
    }

    flav2 {
        flavorGroup 'version'
        packageName 'com.company.flav2'
    }

    flav3 {
        flavorGroup 'version'
        packageName 'com.company.flav3'
    }
}

// .. Other stuff

It works great. All sources and resources are merged correctly. But for specific reasons I need the package suffix to be .amz for the amazon product flavor. How can I achieve that?

I tried this way:

amazon {
    flavorGroup 'market'
    packageNameSuffix '.amz'
}

but gradle throws an exception.