How to link a Gradle project to the Javadoc of its dependencies?

Question

I have a Gradle project consisting of an Android application module. I cannot figure out how to get the Android application module to link into the Javadoc of its dependencies.

I have specified the following in the project's root-level build.gradle file as well the Android application module's build.gradle file:

apply plugin: 'idea'

idea {
    module {
        downloadJavadoc = true
        downloadSources = true
    }
}

I can see by inspecting the ~/.gradle/caches/modules-2/files-2.1 folder on my machine that the Javadoc for the dependencies has indeed been downloaded.

However, when I inspect the xml files in the .idea/libraries folder in my project, I see that the JAVADOC tag is always empty. The CLASSES and SOURCES tags are non-empty and, of course, link correctly to the classes and sources respectively. How can I get IntelliJ to link to the Javadoc also (so that when I press F1 on one of the dependency's classes or methods I see the Javadoc)?

Afterwords

1. I have tried hitting the "Refresh all Gradle projects" button as well as hitting "Invalidate caches / Restart...". That makes no difference.
2. I have tried this on both IntelliJ IDEA Ultimate 2016.3 as well as Android Studio 2.2.3. Same problem on both.
3. I am aware that I can see Javadoc for dependencies of my application which have published Sources. The problem is that some of my application's dependencies have published Javadoc but not Sources.

Answer 1

You can manually specify the JavaDoc location in Project Structure | Libraries | Specify Documentation URL. This will populate JAVADOC element in the .idea/libraries directory. You can point it at a url or download a Javadoc jar.

To get the downloaded jar to work I needed to unzip the jar and point the IntelliJ url to the directory containing the unzipped javadocs. The resulting url would look like file:///tmp/junit with unzipped javadocs being inside the junit directory.

There is a good answer here Attaching additional javadoc in Intellij IDEA