Question: Does such program exist?

I have to study Java SE and diagram with all classes and interfaces from given package will be immensely helpful.

For example I want to plot all relations between subclasses of types Collection and Map.

I know there are a lot of images with core package structure already, but don't really trust them because they are proven to be incomplete, outdated or even inaccurate.

Answer: 
Whilst I don't know of any tools for generating UML class diagrams from JavaDocs, there are many tools available that can generate UML class diagrams from source code, and there are already many [questions on StackOverflow](https://stackoverflow.com/search?q=generate%20uml%20class%20diagram%20from%20java%20code) that suggest various tools that can do this

[This question](https://stackoverflow.com/questions/1687323/from-java-code-to-uml-diagram) seems to have a good range of options that you could explore. I've used [ArgoUML](http://argouml.tigris.org/) myself, but I suggest looking at the options to find the one what appeals to you most.

You can download the [Java SE source code](http://download.java.net/jdk6/source/) and generate the class diagrams for the sections you're interested in.
You can not create diagrams from JavaDoc because there is no official implementation. Only Java code could be reversed and displayed as class or sequence diagrams.

I played to reverse the full Java language with EclipseUML Omondo. It was really interesting to get all dependencies, inheritances, associations at package but also at project level, or even at multi-projects level.

The trick Omondo use is to convert manually each Java Id to a single UML Id. You get after a 30 mn process a huge model composed by hundred of thousands UML Ids saved in an XMI format respecting java project structure. I mean you get project > packages > class> iner classes > attrbites etc...
From this model then you create views by drag and drop or directly selecting the entire package. You can show hide relations, navigate in the code at graphical level etc.....
Really amazing technology !!