Android gradle javadoc

Background

I develop Android SDK at work.
I want to make javadoc for SDK API. For SDK, I don’t want to show private API and not API methods.
So, I tried to make new task to generate javadoc only for SDK public API.

Sample

build.gradle Please add following any place to your build.gradle

android.libraryVariants.all { variant ->
    task generateJavadoc(type: Javadoc, overwrite: true) {
        title = "Reward SDK API"
        description "Generates JavaDoc."
        source = variant.javaCompile.source
        ext.androidJar = "${android.sdkDirectory}/platforms/${android.compileSdkVersion}/android.jar"
        classpath = files(variant.javaCompile.classpath.files) + files(ext.androidJar)
        failOnError = false
        include('com/atmarkplant/sdk/api/**.java');
        options.links("https://docs.oracle.com/javase/8/docs/api/");
        options.linksOffline("https://d.android.com/reference", "${android.sdkDirectory}/docs/reference")
        options.setMemberLevel(JavadocMemberLevel.PUBLIC);
        options.docEncoding("UTF-8");
        options.encoding("UTF-8");
        options.charSet("UTF-8");
    }
    generateJavadoc.dependsOn(clearDoc)
}

include is source target(only public API).

You can run gradle command.

gradle generateJavadoc

Or, double click Android Studio Gradle project panel.
After it, javadoc is under build/docs/javadoc/

options.linksOffline("https://d.android.com/reference", "${android.sdkDirectory}/docs/reference")

This part works when you have Android documentation on your local.

Problem

javadoc main documentation is inside of iframe. Android link and Oracle java link is outside of domain.
I could not jump directly inside and need to use another tab or window.