[news.eclipse.tools] How do I know the available filter names?

[Tobias Müller <TRMueller@xxxxxx>]

Hello,

a little newbie question, so please don't laugh.

If I contribute (objectContribution) for example a popup menu action, I 
can specify a filter (<filter name="..." value="...">), so the Platform 
will try to retrieve an IActionFilter object from the selected item and 
look if the name/value-pair is matching. (Am I right this far?)

But how do I know what kind of "names" (or keys) there are available? 
IProject for example has a name "projectNature", so I can check whether 
or not the selected Project has the expected project nature. But how do 
I know there exists something like a "projectNature"-name/key?

I couldn't find an answer to this (probably easy) question. Maybe you 
can help. (I hope this question is not too stupid.)

Thanks!
Tobias