Define buildconfigfield for an specific flavor AND buildType

Loop the variants and check their names:

productFlavors {
    vanilla {}
    chocolate {}
}

applicationVariants.all { variant ->
    println("Iterating variant: " + variant.getName())
    if (variant.getName() == "chocolateDebug") {
        variant.buildConfigField "boolean", "VARIABLE", "true"
    } else {
        variant.buildConfigField "boolean", "VARIABLE", "false"
    }
}