[generatereleaseJavadoc] task config

buiild.gradle

android.libraryVariants.all { variant ->

    task("generate${variant.name}Javadoc", type: Javadoc) {
        title = "$name $version API"
        description "Generates Javadoc for $variant.name."
        source = variant.javaCompile.source
        ext.androidJar =
                "${android.sdkDirectory}/platforms/${android.compileSdkVersion}/android.jar"
        classpath = files(variant.javaCompile.classpath.files) + files(ext.androidJar)
        options.links("http://docs.oracle.com/javase/7/docs/api/");
        options.links("http://d.android.com/reference/");
        options.encoding("utf-8")
        exclude '**/BuildConfig.java'
        exclude '**/R.java'
    }

}