I am trying to link into some Javadocs hosted at javadoc.io (specifically, PowerMock's Javadocs) using the `@link` option. I have tried to add the URL to PowerMock's Javadocs to my `-link` flag, but can't get Javadoc to recognize it. I am using external links to other Javadocs just fine (e.g. Guava, Java SE 7) with Gradle as my build system. I have tried the following options:

`-link http://static.javadoc.io/org.powermock/powermock-core/1.6.3/`

^ I have confirmed that there is a `package-list` file in this directory

`-link http://static.javadoc.io/org.powermock/powermock-core/`

`-link http://javadoc.io/doc/org.powermock/powermock-core/1.6.3/`

`-link http://javadoc.io/doc/org.powermock/powermock-core/`

All of these result in the following error (URL changed accordingly):

`javadoc: warning - Error fetching URL: http://static.javadoc.io/org.powermock/powermock-core/1.6.3/`

Does anyone have advice on how to make this work?

As far as I can tell this is some sort of javadoc.io specific problem, though likely a usage issue on my end - for example I am currently using `-link http://junit.org/javadoc/latest/` without issue, but `-link http://static.javadoc.io/junit/junit/4.12/` doesn't work.